Semiconductor device

Abstract

To provide a method for manufacturing a semiconductor device capable of providing a stable electric property and high reliability to the semiconductor device using an oxide semiconductor.SOLUTION: A method for manufacturing a semiconductor device comprises the steps of: forming a first insulating film; forming, on the first insulating film, a source electrode and a drain electrode, and an oxide semiconductor flim which electrically connects the source electrode and the drain electrode; removing hydrogen atoms in the oxide semiconductor film by subjecting the oxide semiconductor film to heat treatment; supplying oxygen atoms into the oxide semiconductor film by subjecting the oxide semiconductor film from which the hydrogen atoms are removed to oxygen doping treatment; forming a second insulating film on the oxide semiconductor film to which the oxygen atoms are supplied; and forming a gate electrode in a region superimposed on the oxide semiconductor film on the second insulating film.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a semiconductor device and a method for manufacturing the semiconductor device.

[0002] In this specification, a semiconductor device is a device that can function by utilizing semiconductor characteristics. The term "semiconductor device" refers to devices in general, and electro-optical devices, semiconductor circuits, and electronic equipment are all semiconductor devices. [Background technology]

[0003] A technology for constructing transistors using semiconductor thin films formed on substrates with insulating surfaces These transistors are used in integrated circuits (ICs) and image display devices (display devices). It is widely used in such electronic devices. Silicon-based semiconductor materials are widely known, but oxide semiconductors are also attracting attention. are.

[0004] For example, the active layer of a transistor is 18 / cm 3 Less than The amorphous oxide containing indium (In), gallium (Ga), and zinc (Zn) is used. A transistor using this method has been disclosed (see Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-165528 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the device manufacturing process, oxide semiconductors are formed by the addition of hydrogen and water, which form electron donors. If contamination occurs, the electrical conductivity may change. This is a factor that causes fluctuations in the electrical characteristics of semiconductor transistors.

[0007] In view of the above-mentioned problems, the present invention provides a semiconductor device using an oxide semiconductor with stable electrical characteristics, One of the objectives is to achieve high reliability. [Means for solving the problem]

[0008] In a manufacturing process of a transistor including an oxide semiconductor film, dehydration or Dehydrogenation treatment and oxygen doping treatment are performed. In the manufacturing process of the transistor, oxygen doping treatment is performed.

[0009] One embodiment of the disclosed invention is a semiconductor device including: a first insulating film; a source electrode and a second insulating film; and a drain electrode, and an oxide semiconductor electrically connected to the source electrode and the drain electrode. A conductive film is formed, and the oxide semiconductor film is subjected to heat treatment to remove hydrogen atoms in the oxide semiconductor film. Then, oxygen doping treatment is performed on the oxide semiconductor film from which the hydrogen atoms have been removed, and and forming a second insulating film on the oxide semiconductor film to which oxygen atoms have been supplied. a gate electrode formed in a region overlapping with the oxide semiconductor film on the second insulating film; This is the manufacturing method.

[0010] Another embodiment of the disclosed invention is a method for forming a first insulating film containing oxygen atoms as a component, The insulating film is subjected to oxygen doping treatment to supply oxygen atoms to the first insulating film, and The source electrode and the drain electrode, and the source electrode and the drain electrode and the and forming an oxide semiconductor film connected to the oxide semiconductor layer by performing heat treatment on the oxide semiconductor film. The hydrogen atoms in the oxide semiconductor film are removed, and oxygen doping treatment is performed on the oxide semiconductor film from which the hydrogen atoms have been removed. oxygen atoms are supplied into the oxide semiconductor film, and a deposition layer is formed on the oxide semiconductor film to which the oxygen atoms have been supplied. A second insulating film containing oxygen atoms as a component is formed, and the second insulating film is subjected to oxygen doping treatment. oxygen atoms are supplied to the second insulating film, and a region of the second insulating film overlapping with the oxide semiconductor film is This is a method for manufacturing a semiconductor device in which a gate electrode is formed.

[0011] In the above, oxygen atoms are included in a ratio of more than 1 to 2 times the stoichiometric ratio. In some cases, the oxide semiconductor film is doped. In some cases, an insulating film containing a component element of the oxide semiconductor film is formed as the first film. an insulating film containing a component element of an oxide semiconductor film as the insulating film or the second insulating film; In some cases, a film containing an element different from the component element of the film is formed. The second insulating film may be an insulating film containing gallium oxide. As the insulating film or second insulating film, an insulating film containing gallium oxide and an insulating film other than gallium oxide are used. In this specification, the term "gallium oxide" is used to refer to a material that is used for forming a film. The term refers to the constituent elements oxygen and gallium unless otherwise specified. However, the term "insulating film containing gallium oxide" is not intended to be limited to the embodiment of gallium oxide. In this case, it can be read as "an insulating film containing oxygen and gallium."

[0012] In the above, when an insulating film containing nitrogen is formed so as to cover the gate electrode, In this way, silicon nitride or the like that does not contain or contains very little hydrogen is present above. When forming an insulating film using the above, it is necessary to prevent the added oxygen from being released to the outside. This makes it possible to prevent the intrusion of hydrogen and water from the outside. It can be said that it is highly important.

[0013] The above "oxygen doping" refers to the doping of a material with oxygen (at least oxygen radicals, oxygen atoms, oxygen This refers to the addition of a substance (including any of the above) to the bulk. The term "oxygen addition" is used to clarify that oxygen is added not only to the surface of the thin film but also to the inside of the thin film. In addition, "oxygen doping" involves adding plasma oxygen to the bulk. Includes "Zumadope".

[0014] The oxygen doping treatment described above allows oxygen to be doped into the oxide semiconductor film (bulk) and the insulating film ( In either the bulk or the interface between the oxide semiconductor film and the insulating film, a ratio exceeding the stoichiometric ratio is present. The amount of oxygen is preferably greater than 1 to 4 times the stoichiometric ratio ( less than 4 times), more preferably more than 1 time to 2 times (less than 2 times). Oxide with excess oxygen beyond the stoichiometric ratio is, for example, In a Ga b Zn c Si d Al e Mg f O g When expressed as (a, b, c, d, e, f, g ≥ 0), 2g > 3a + 3b + It refers to an oxide that satisfies the formula 2c+4d+3e+2f. Note that the oxide is added by oxygen doping. Oxygen may also exist between lattices of the oxide semiconductor.

[0015] In addition, the amount of hydrogen added is greater than that in the oxide semiconductor film after dehydration and dehydrogenation. The amount of oxygen added in at least one of the above configurations is increased. If the amount of hydrogen is greater than that of the hydrogen, it will diffuse and react with the hydrogen, which causes other instabilities. This allows hydrogen to be immobilized (immobile ionized). In addition, excess oxygen can reduce or even completely eliminate the oxygen deficiency that occurs when oxygen is used. The variation in the threshold voltage Vth due to the h can be reduced.

[0016] In addition, in the oxide semiconductor film (bulk), in the insulating film (bulk), in the oxide semiconductor It is more preferable that the above amount of oxygen is present at two or more locations: the interface between the film and the insulating film.

[0017] In the case of an oxide semiconductor without defects (oxygen vacancies), the amount of oxygen that matches the stoichiometric ratio However, it is necessary to ensure reliability by suppressing fluctuations in the threshold voltage of transistors. To ensure this, the oxide semiconductor must contain oxygen in an amount exceeding the stoichiometric ratio. Similarly, if the oxide semiconductor has no defects (oxygen vacancies), the base film is preferably formed by using an oxygen-excessive It is not necessary to use an insulating film, but it is necessary to improve reliability by suppressing fluctuations in the threshold voltage of the transistor. In order to ensure this, the underlayer film is formed by taking into consideration that oxygen vacancies may occur in the oxide semiconductor layer. It is preferable that the insulating film contains excess oxygen.

[0018] Here, the above-mentioned "oxygen plasma doping" process allows oxygen to be added to the bulk. Note that when oxygen doping treatment is performed on an oxide semiconductor film containing oxygen as one of its components, Generally, it is difficult to confirm the increase or decrease in oxygen concentration. The effect of oxygen doping was confirmed using an EHA.

[0019] The oxygen doping process was carried out using inductively coupled plasma (ICP). The conditions were ICP power 800 W, RF bias Gas power 300W or 0W, pressure 1.5Pa, oxygen gas flow rate 75sccm, substrate temperature 7 0°C. Figure 15 shows the SIMS (Secondary Ion Mass Spectrometry) 1 shows the oxygen concentration profile in the depth direction of a silicon wafer obtained by a rheometry analysis. In FIG. 15, the vertical axis indicates the oxygen concentration, and the horizontal axis indicates the depth from the surface of the silicon wafer.

[0020] From Figure 15, when the RF bias power is either 0W or 300W, It can be confirmed that oxygen is added. In addition, when the RF bias is 300 W, It can be seen that oxygen is doped deeper than when the bias is 0 W.

[0021] Next, the cross section of the silicon wafer before and after oxygen doping was measured using S TEM(Scanning Transmission Electron Micro The results of observation by scopy are shown in Figure 16. Figure 16(A) shows the state before oxygen doping treatment. Fig. 16(B) shows the STEM image of the oxygen doped SiO2 film under the RF bias power of 300 W. As shown in Figure 16(B), the STEM image after oxygen doping was performed. This confirms that a highly oxygen-doped region is formed in the silicon wafer.

[0022] As described above, by doping the silicon wafer with oxygen, the silicon wafer is This result indicates that oxygen doping of the oxide semiconductor film is effective. It can be understood that oxygen can be naturally added to the oxide semiconductor film by performing the above-mentioned method.

[0023] The effect of the above-described configuration, which is one embodiment of the disclosed invention, can be easily understood by considering it as follows. However, please note that the following explanation is merely one consideration.

[0024] When a positive voltage is applied to the gate electrode, the oxide semiconductor film is back-turned from the gate electrode side. Since an electric field is generated on the channel side (opposite to the gate insulating film), Positively charged hydrogen ions move to the back channel side and form an insulating layer with the oxide semiconductor film. The accumulated hydrogen ions are transferred to the oxide semiconductor film side of the interface with the insulating film. By transferring a positive charge to a charge capture center (such as a hydrogen atom, water, or pollutant) In this case, negative charges are accumulated on the back channel side of the oxide semiconductor film. A parasitic channel occurs on the back channel side of the transistor, causing the threshold voltage to shift to the negative side. The transistor tends to be normally on.

[0025] As mentioned above, charge trapping centers such as hydrogen or water in the insulating film capture positive charges and form an insulating film. The electrical characteristics of the transistor change when a positive charge moves into the film. To suppress the fluctuation of the electrical characteristics of the transistor, it is necessary to eliminate these charge trapping centers in the insulating film. Therefore, it is important that the insulating film is not formed or that the content of the insulating film is small. For this purpose, it is desirable to use a sputtering method that has a low hydrogen content during film formation. The insulating film formed has no or few charge trapping centers in the film, and is formed by a method such as CVD. Compared to when the film is formed by the This suppresses the shift in the threshold voltage of the transistor, making it normally off. .

[0026] In a top-gate transistor, an oxide semiconductor is formed on an insulating film serving as a base. After the film is formed, heat treatment is performed to remove water or hydrogen contained in the oxide semiconductor film. At the same time, water or hydrogen contained in the insulating film can be removed. There are charge trapping centers in the film that capture positive charges that have moved through the oxide semiconductor film. Thus, the heat treatment for dehydration or dehydrogenation of the oxide semiconductor film is performed without using an acid. This is because the treatment is performed not only on the oxide semiconductor film but also on the insulating film underneath the oxide semiconductor film. In the case of top-gate transistors, the insulating film that serves as the base is formed by plasma CVD or other methods. The film may be formed using a CVD method.

[0027] When a negative voltage is applied to the gate electrode, the back channel Because an electric field is generated in the oxide semiconductor film, hydrogen ions in the oxide semiconductor film move to the gate insulating film side. The oxide semiconductor film and the gate insulating film are then accumulated on the oxide semiconductor film side of the interface between the oxide semiconductor film and the gate insulating film. This also shifts the threshold voltage of the transistor to the negative side.

[0028] If the voltage is set to 0 and the device is left alone, the positive charge is released from the charge trapping center, and the transistor The threshold voltage of the transistor shifts to the positive side, returning to the initial state, or This phenomenon occurs because the charge tends to move into the oxide semiconductor film. This suggests that ions exist, and hydrogen, the smallest atom, is the most mobile. It can be considered that the ions

[0029] In addition, the oxide semiconductor film absorbs light, and the oxide semiconductor is converted by the light energy. The bond between a metal element (M) and a hydrogen atom (H) in the body membrane (also called an M-H bond) breaks The light energy with a wavelength of around 400 nm and the bond energy between metal elements and hydrogen atoms The bond between the metal element and the hydrogen atom in the oxide semiconductor film is broken. When a negative gate bias is applied to a transistor, hydrogen ions desorbed from the metal element are transported to the gate. The charge distribution changes as the charge is attracted to the gate electrode, and the threshold voltage of the transistor decreases. The graph shifts to the eggplant side, showing a tendency toward normally-on.

[0030] In addition, the gate insulating film interface is etched by applying light to the transistor and a negative gate bias. The hydrogen ions that have moved to the oxide semiconductor film return to their original state when the voltage application is stopped. This can be understood as a typical example of ion migration.

[0031] Such fluctuations in electrical characteristics due to voltage application (BT degradation) or electrical characteristics due to light irradiation Countermeasures against fluctuations in characteristics (photodegradation) include the removal of hydrogen atoms or hydrogen atoms such as water from the oxide semiconductor film. It is most important to thoroughly remove impurities including fluorine and to highly purify the oxide semiconductor film. Charge density is 10 15 cm -3 , that is, the charge per unit area is 10 10 cm -2 in the case of The charge does not affect the transistor characteristics, or if it does, it only affects them slightly. So the charge density is 10 15 cm -3 If the oxide semiconductor film When 10% of the contained hydrogen moves in the oxide semiconductor film, the hydrogen concentration is 1 0 16 cm -3 Furthermore, after the device is completed, hydrogen is infiltrated from the outside. To prevent the intrusion of silicon dioxide, a silicon nitride film formed by sputtering is used as a passivation film. It is preferably used as a film to cover the transistor.

[0032] Furthermore, excess oxygen is doped into the hydrogen contained in the oxide semiconductor film (hydrogen By setting the number of atoms as the number of oxygen radicals or the number of oxygen ions, it is possible to obtain an oxide. It is possible to remove hydrogen or water from the semiconductor film. The oxygen is converted into plasma by increasing the substrate bias, and oxygen radicals and oxygen ions are generated on the substrate. The oxide semiconductor film is doped or added with oxygen rather than hydrogen remaining in the oxide semiconductor film. The electronegativity of oxygen is 3.0, and the electronegativity of the oxide semiconductor film is about 2.0. Since it is larger than the metals in the middle (Zn, Ga, In), it contains an excess of oxygen relative to hydrogen. This removes hydrogen from the MH group and forms an OH group. This can form an MOH group.

[0033] Note that oxygen is doped so that the oxygen content in the oxide semiconductor film becomes larger than the stoichiometric ratio. For example, an In-Ga-Zn-O oxide semiconductor film is preferably used. When using a semiconductor film, the oxygen ratio is increased to more than 1 times the stoichiometric ratio by oxygen doping or the like. It is more preferable to set the ratio to less than 2 times. For example, in the case of an In-Ga-Zn-O system oxide If the stoichiometric ratio of a single crystal of a compound semiconductor is In:Ga:Zn:O=1:1:1:4, The composition is InGaZnO x In the oxide semiconductor thin film represented by the formula: X is more than 4 and less than 8. Therefore, the oxygen content in the oxide semiconductor film is preferably higher than the hydrogen content. Get bigger.

[0034] Light energy and BT stress cause hydrogen to be released from the MH group, which causes deterioration. However, when oxygen is implanted by the above-mentioned doping, the implanted oxygen combines with hydrogen ions and The OH group has a large bond energy, so it is difficult to apply light or BT switch to the transistor. It does not release hydrogen ions when stress is applied, and its mass is larger than that of hydrogen ions. Therefore, the OH group formed by the doping of oxygen is difficult to move in the oxide semiconductor film. , the deterioration of the transistors is not caused or the cause of the deterioration can be reduced.

[0035] Note that the larger the thickness of the oxide semiconductor film, the greater the variation in threshold voltage of the transistor. It has been confirmed that the threshold voltage tends to increase. This is presumably due to the fact that the oxygen defects increase as the film thickness increases. In the transistor of one embodiment of the present invention, the step of doping the oxide semiconductor film with oxygen includes: Not only can hydrogen or water be removed from the oxide semiconductor film, but oxygen defects in the film can also be compensated for. Therefore, the transistor according to one embodiment of the present invention can effectively suppress variations in threshold voltage. It can be controlled.

[0036] In addition, a metal oxide film made of the same kind of component as the oxide semiconductor film is provided between the oxide semiconductor film. The structure using the same material as the oxide semiconductor film is also effective in preventing fluctuations in electrical characteristics. Specifically, the metal oxide film may be formed of one or more elements selected from the component elements of an oxide semiconductor film. It is preferable to use a film containing an oxide of several metal elements. By providing the metal oxide film between the oxide semiconductor film and the metal oxide film, In other words, the metal oxide film using the above-mentioned material can maintain a good interface state with the film. is provided as an insulating film in contact with the oxide semiconductor film, This can suppress or prevent the accumulation of hydrogen ions at the interface with the membrane and in the vicinity thereof. Therefore, for example, a silicon oxide film or the like, which is different from an oxide semiconductor film, is sandwiched between the oxide semiconductor film and the silicon oxide film. The threshold voltage of the transistor is not affected as compared with the case where an insulating film made of a material other than silicon is provided. Therefore, the hydrogen concentration at the interface of the oxide semiconductor film can be sufficiently reduced.

[0037] It is preferable to use a gallium oxide film as the metal oxide film. Since the band gap (Eg) is large, the oxide semiconductor film is sandwiched between gallium oxide films. As a result, an energy barrier is formed at the interface between the oxide semiconductor film and the metal oxide film. Therefore, the carriers are prevented from moving at the interface. On the other hand, hydrogen ions move through the oxide semiconductor film without moving from the metal oxide to the The electrons pass through the interface between the oxide semiconductor and the metal oxide and accumulate near the interface between the metal oxide and the insulating film. Even if hydrogen ions are accumulated near the interface with the insulating film, they are not absorbed by the metal oxide film. The gallium oxide film used as the transistor does not form a parasitic channel through which carriers can flow. The effect on the threshold voltage of the transistor is minimal or not. When gallium is in contact with an In-Ga-Zn-O material, the energy barrier is the conduction band. It is about 0.8 eV on the side of the electron band and about 0.9 eV on the side of the valence band.

[0038] In a transistor according to one embodiment of the disclosed invention, an oxide semiconductor At least one of an insulating film in contact with the film, an oxide semiconductor film, and a vicinity of the interface between them First, the technical idea is to increase the oxygen content.

[0039] When an oxide semiconductor material containing indium is used for the oxide semiconductor film, Since the bonding strength of oxygen is relatively weak, the insulating film in contact with the oxide semiconductor film is When the oxide semiconductor film contains a material that has strong bonding strength with the oxide semiconductor film, oxygen in the oxide semiconductor film is removed by heat treatment. As a result, oxygen vacancies may be formed near the interface of the oxide semiconductor film. On the other hand, in a transistor according to one embodiment of the disclosed invention, excess oxygen is supplied to an oxide semiconductor film. By supplying oxygen, the formation of oxygen vacancies can be suppressed.

[0040] Here, after the oxygen doping treatment is performed in the manufacturing process of the transistor, the oxide semiconductor The amount of oxygen contained in the insulating film in contact with the oxide semiconductor film or the oxide semiconductor film in excess of the stoichiometric ratio The amount of excess oxygen may be different in each layer. The difference in chemical potential is due to the heat treatment in the transistor manufacturing process. It is thought that the equilibrium state will be approached or reached due to the following reasons. We will consider the distribution of oxygen in the

[0041] At a certain temperature T and pressure P, the equilibrium state is one in which the Gibbs free energy G of the entire system is minimized. This is the state, which is expressed by the following equation (1).

[0042]

number

[0043] In equation (1), G (1) , G (2) , G (3) is the Gibbs free energy of each layer Also, N a , N b , N c represents the number of particles, and a, b, and c represent the types of particles. a is δN from layer i to layer j a (j) If only one molecule moves, the change in Gibbs free energy is This is expressed as the following equation (2).

[0044]

number

[0045] Here, when ΔG is 0, that is, when the following equation (3) holds, the system is in equilibrium.

[0046]

number

[0047] The particle number derivative of the Gibbs free energy corresponds to the chemical potential, so in equilibrium At this point, the chemical potential of the particles is equal in all layers.

[0048] Specifically, when the oxide semiconductor film contains more oxygen than the insulating film, In this case, the chemical potential of oxygen is relatively small in the insulating film, and the chemical potential of oxygen is relatively small in the oxide semiconductor film. The potential is relatively large.

[0049] Then, by performing heat treatment in the manufacturing process of the transistor, the entire system (here The temperature of the oxide semiconductor film and the insulating film in contact with it becomes high enough that the atoms in the layers and between the layers When diffusion begins, oxygen moves so that the chemical potentials are the same. That is, oxygen in the oxide semiconductor film moves to the insulating film, and the chemical potential of the oxide semiconductor film increases. The potential of the insulating film becomes smaller and the chemical potential of the insulating film becomes larger.

[0050] Therefore, the oxygen supplied to the oxide semiconductor film in excess by the oxygen doping treatment is By bringing the chemical potential in the system into equilibrium through subsequent heat treatment, the insulating film ( Therefore, when there is a sufficient amount of excess oxygen in the oxide semiconductor film, In this case, the insulating film in contact with the oxide semiconductor film (including the interface) may also have an oxygen excess.

[0051] Therefore, the amount of oxygen sufficient to compensate for the oxygen deficiency defects in the insulating film or the interface with the insulating film (oxygen deficiency By supplying oxygen (an excessive amount that more than compensates for defects) into the oxide semiconductor film, is said to have great significance. [Effects of the Invention]

[0052] Oxide semiconductors that have been subjected to dehydration or dehydrogenation treatment by heat treatment and oxygen doping treatment The transistor with the film exhibited excellent thermal conductivity before and after the bias-thermal stress (BT) test. The amount of change in the threshold voltage of the transistor is reduced, resulting in a highly reliable device with stable electrical characteristics. A transistor can be realized.

[0053] According to one embodiment of the disclosed invention, a highly reliable transistor with favorable electrical characteristics can be obtained. Various semiconductor devices can be manufactured. [Brief explanation of the drawings]

[0054] [Figure 1] 1A to 1C illustrate one embodiment of a semiconductor device. [Figure 2] 1A to 1C illustrate one embodiment of a method for manufacturing a semiconductor device. [Figure 3] 1A to 1C illustrate modes of a semiconductor device. [Figure 4] 1A to 1C illustrate one embodiment of a method for manufacturing a semiconductor device. [Figure 5] 1A to 1C illustrate one embodiment of a method for manufacturing a semiconductor device. [Figure 6] 1A to 1C illustrate one embodiment of a manufacturing method of a semiconductor device. [Figure 7] 1A to 1C are a cross-sectional view, a top view, and a circuit diagram of a semiconductor device. [Figure 8] 1A to 1C illustrate one embodiment of a semiconductor device. [Figure 9] 1A to 1C illustrate one embodiment of a semiconductor device. [Figure 10] 1A to 1C illustrate one embodiment of a semiconductor device. [Figure 11] 1A to 1C illustrate one embodiment of a semiconductor device. [Figure 12] 1A to 1C illustrate one embodiment of a semiconductor device. [Figure 13] 1A and 1B are diagrams illustrating electronic devices. [Figure 14] 1A and 1B are diagrams illustrating electronic devices. [Figure 15] FIG. 10 is a diagram showing the results of SIMS measurements. [Figure 16] FIG. 1 is a diagram illustrating a cross-sectional STEM image. [Figure 17] 1A and 1B are a top view and a cross-sectional view of a plasma device. DETAILED DESCRIPTION OF THE INVENTION

[0055] Hereinafter, embodiments of the invention disclosed in this specification will be described in detail with reference to the drawings. However, the invention disclosed in this specification is not limited to the following description, and various modes and details may be used. It will be readily understood by those skilled in the art that various modifications may be made to the invention disclosed herein. The present invention should not be construed as being limited to the description of the following embodiments.

[0056] In this specification, ordinal numbers such as "first," "second," and "third" refer to the order of components. It should be noted that this is added to avoid confusion and is not intended to limit the number.

[0057] (Embodiment 1) In this embodiment mode, a semiconductor device and a manufacturing method of the semiconductor device will be described with reference to FIGS. This will be used to explain.

[0058] <Configuration Example of Semiconductor Device> FIG. 1 illustrates a structural example of the transistor 120. Here, FIG. 1A is a plan view. Figure 1(B) and Figure 1(C) are cross sections AB and CD in Figure 1(A), respectively. In order to avoid complication, FIG. 1(A) shows the transistor. Some of the components of the gate 120 (for example, the gate insulating film 110) are omitted.

[0059] The transistor 120 shown in FIG. 1 includes an insulating film 102 on a substrate 100, a source electrode 104a, and a , the drain electrode 104b, the oxide semiconductor film 108, the gate insulating film 110, and the gate electrode 11 Includes 2.

[0060] In the transistor 120 illustrated in FIG. 1, the oxide semiconductor film 108 is doped with oxygen. The oxide semiconductor film is subjected to oxygen doping treatment. The transistor 120 is realized.

[0061] <Example of a manufacturing process for a semiconductor device> An example of a manufacturing process of the semiconductor device shown in FIG. 1 will be described below with reference to FIG.

[0062] First, an insulating film 102 is formed on a substrate 100 (see FIG. 2(A)).

[0063] There is no particular restriction on the material of the substrate 100, but it should be at least durable enough to withstand the subsequent heat treatment. For example, glass substrates, ceramic substrates, quartz substrates, A sapphire substrate or the like can be used as the substrate 100. In addition, silicon or silicon carbide Single crystal semiconductor substrates such as silicon, polycrystalline semiconductor substrates, compounds such as silicon germanium It is also possible to apply a semiconductor substrate, an SOI substrate, etc., and a semiconductor element is formed on these substrates. may be used as the substrate 100.

[0064] A flexible substrate may be used as the substrate 100. When providing the transistor, the transistor may be directly formed on the flexible substrate, or the transistor may be formed on another substrate. After the transistor is formed, it may be peeled off and transferred to a flexible substrate. In order to peel off the transistor and transfer it to a flexible substrate, a peeling It is advisable to form a separation layer.

[0065] The insulating film 102 is an insulating film that functions as a base. Specifically, the insulating film 102 includes: Silicon oxide, silicon nitride, aluminum oxide, aluminum nitride, gallium oxide, The insulating film 102 may be an insulating film containing any of the above materials. The film may have a single layer structure or a laminated structure.

[0066] There is no particular limitation on the method for producing the insulating film 102. For example, plasma CVD or sputtering may be used. The insulating film 102 can be formed by a deposition method such as a deposition method using hydrogen, water, etc. The sputtering method is preferable in that it is less likely to be mixed with other metals.

[0067] The insulating film 102 is made of an insulating material containing the same components as the oxide semiconductor film to be formed later. It is particularly preferable to use such a material. Such a material is compatible with the oxide semiconductor film and can insulate the oxide semiconductor film. By using the film 102, the state of the interface with the oxide semiconductor film can be kept good. Here, the term "component of the same kind as the oxide semiconductor film" refers to a component element of the oxide semiconductor film. For example, the oxide semiconductor film may be an In-Ga-Zn When it is composed of -O-based oxide semiconductor material, insulating materials made of the same components include Gallium oxide, etc.

[0068] In addition, when the insulating film 102 has a stacked structure, the insulating film 102 should be made of the same material as the oxide semiconductor film. A membrane made of a different material (hereinafter referred to as membrane a) and a membrane containing a different material from the component material of membrane a (hereinafter referred to as membrane b) ) is preferably a stacked structure. By doing so, the charges are preferentially captured by the charge capture centers at the interface between film a and film b (oxide (Comparison with the interface between the semiconductor film and film a) Therefore, charge trapping at the interface of the oxide semiconductor film is sufficiently suppressed. This is because it is possible to control the temperature and improve the reliability of the semiconductor device.

[0069] Such a laminated structure may include a laminated structure of a gallium oxide film and a silicon oxide film, A laminated structure of a gallium oxide film and a silicon nitride film can be applied.

[0070] Next, a source electrode and a drain electrode (formed in the same layer as this) are formed on the insulating film 102. A conductive film for forming a source electrode 1 is formed by processing the conductive film. Then, a gate electrode 104a and a drain electrode 104b are formed (see FIG. 2(B)). The distance between the end of the source electrode 104a and the end of the drain electrode 104b determines the The channel length L of the transistor is determined.

[0071] The conductive film used for the source electrode 104a and the drain electrode 104b is, for example, a metal film containing an element selected from the group consisting of I, Cr, Cu, Ta, Ti, Mo, and W, or the above-mentioned Metal nitride films containing elements (titanium nitride film, molybdenum nitride film, tungsten nitride film) ) and the like. In addition, Ti, Cu, etc. are used on either the upper or lower side of the metal film or both sides. High-melting metal films such as Mo and W, or metal nitride films (titanium nitride film, molybdenum nitride film, etc.) Alternatively, a conductive film in which a tungsten nitride film, a tungsten nitride film, or the like is stacked may be used.

[0072] The conductive film used for the source electrode 104a and the drain electrode 104b is a conductive gold film. It may be formed of a metal oxide. An example of a conductive metal oxide is indium oxide (In2O3). , tin oxide (SnO2), zinc oxide (ZnO), indium oxide tin oxide alloy (In2O 3-SnO2, abbreviated as ITO), indium oxide zinc oxide alloy (In2O3-ZnO ) or a material obtained by adding silicon oxide to these metal oxide materials can be used.

[0073] The conductive film can be processed by etching using a resist mask. The exposure to light when forming the resist mask used for etching is ultraviolet light, KrF laser light, or ArF It is advisable to use a laser beam or the like.

[0074] When performing exposure with a channel length L of less than 25 nm, for example, several nm to several tens of nm Using extreme ultraviolet light with an extremely short wavelength of 1000m, It is recommended to perform exposure when forming a resist mask. Exposure with extreme ultraviolet light has high resolution and focal depth. Therefore, the channel length L of the transistor to be formed later can be reduced. This makes it possible to increase the operating speed of the circuit.

[0075] In addition, etching is performed using a resist mask formed by a so-called multi-tone mask. The resist mask formed using the multi-tone mask has a plurality of film thicknesses. The shape can be further changed by ashing, It can be used in multiple etching processes to process into patterns. A multi-tone mask allows for resist masks that correspond to at least two different patterns. In other words, the process can be simplified.

[0076] Next, an acid film is formed on the insulating film 102 in contact with the source electrode 104a and the drain electrode 104b. An oxide semiconductor film is formed, and the oxide semiconductor film is processed to form an island-shaped oxide semiconductor film 106. (See Figure 2(C)).

[0077] The oxide semiconductor film is preferably formed by a method that does not easily allow hydrogen, water, or the like to be mixed in. The oxide semiconductor film can be formed by a method such as sputtering. The thickness of the oxide semiconductor film is preferably 3 nm to 30 nm. For example, if the film thickness is 50 nm or more, the transistor may become normally on. This is the case.

[0078] The material used for the oxide semiconductor film is, for example, an oxide semiconductor material containing indium. and oxide semiconductor materials containing indium and gallium.

[0079] In addition, the material used for the oxide semiconductor film is In-Sn-G, which is a quaternary metal oxide. a-Zn-O based materials, ternary metal oxide In-Ga-Zn-O based materials, In -Sn-Zn-O based materials, In-Al-Zn-O based materials, Sn-Ga-Zn-O based materials Materials, Al-Ga-Zn-O based materials, Sn-Al-Zn-O based materials, and binary metal oxides In-Zn-O based materials, Sn-Zn-O based materials, and Al-Zn-O based materials are oxides. , Zn-Mg-O based materials, Sn-Mg-O based materials, In-Mg-O based materials, In- Ga-O based materials, In-O based materials, Sn-O based materials, Z nO-based materials. The above materials may also contain silicon oxide. For example, In-Ga-Zn-O-based materials are made of indium (In), gallium (Ga), and zinc. It means an oxide film containing lead (Zn), and the composition ratio is not particularly important. Elements other than n, Ga, and Zn may be included.

[0080] The oxide semiconductor film has the chemical formula InMO3(ZnO) m Materials expressed as (m>0) Here, M is selected from Ga, Al, Mn and Co. For example, M may be Ga, Ga and Al, Ga and and Mn, or Ga and Co, etc. can be used.

[0081] When an In-Zn-O based material is used as the oxide semiconductor film, the target to be used is The composition ratio of In:Zn is 50:1 to 1:2 in atomic ratio (converted to InO In:ZnO=25:1 to 1:4), preferably In:Zn=20:1 to 1:1 (molar ratio In terms of conversion, In2O3:ZnO=10:1 to 1:2), more preferably In:Zn=1 5:1 to 1.5:1 (converted to a molar ratio of In2O3:ZnO = 15:2 to 3:4) For example, the target used to form an In-Zn-O-based oxide semiconductor has an atomic ratio of I When n:Zn:O=X:Y:Z, Z>1.5X+Y.

[0082] In this embodiment, the oxide semiconductor film is formed using an oxide semiconductor film forming method using an In—Ga—Zn—O-based oxide semiconductor film forming method. The film is formed by sputtering using a target.

[0083] As a target for forming an In-Ga-Zn-O-based oxide semiconductor film, for example, the composition ratio and For oxide semiconductor film formation with In2O3:Ga2O3:ZnO=1:1:1 [molar ratio] It should be noted that the material and composition of the target are not limited to those described above. For example, the composition of In2O3:Ga2O3:ZnO=1:1:2 [molar ratio] A target for forming an oxide semiconductor film can also be used.

[0084] The filling rate of the oxide semiconductor film forming target is 90% or more and 100% or less, preferably 95% or less. % or more and 99.9% or less. Use a target for oxide semiconductor film formation with a high filling rate. This is because the formed oxide semiconductor film can be a dense film.

[0085] The film formation atmosphere is a rare gas (typically argon) atmosphere, an oxygen atmosphere, or a rare The oxide semiconductor film may be heated under a mixed atmosphere of hydrogen, water, hydroxyl, or the like. To prevent contamination with hydrogen, water, hydroxyl groups, hydrides, etc., It is desirable to use an atmosphere using a high-purity gas from which impurities, including fluorine, have been sufficiently removed.

[0086] More specifically, for example, the oxide semiconductor film can be formed as follows.

[0087] First, the substrate 100 is held in a film-forming chamber maintained in a reduced pressure state, and the substrate temperature is increased to 100° C. or higher. The temperature is set to 600° C. or less, preferably 200° C. or more and 400° C. or less. By forming the oxide semiconductor film in this state, the impurity concentration in the oxide semiconductor film can be reduced. In addition, damage to the oxide semiconductor film caused by sputtering can be reduced. This is the case.

[0088] Next, while removing the remaining moisture in the film-forming chamber, impurities containing hydrogen atoms such as hydrogen and water are removed. A sufficiently purified high purity gas is introduced, and an oxide semiconductor is deposited on the substrate 100 using the target. To remove the residual moisture in the deposition chamber, a cryostat is used as an exhaust means. Using adsorption type vacuum pumps such as pumps, ion pumps, and titanium sublimation pumps It is desirable that the exhaust means be a turbo molecular pump with a cold trap added. The film formation chamber evacuated using a cryopump may contain, for example, hydrogen molecules and water. Compounds containing hydrogen atoms such as (HO) (and more preferably compounds containing carbon atoms) Since the impurities are removed, the concentration of impurities contained in the oxide semiconductor film formed in the film formation chamber can be reduced. It can be reduced.

[0089] As an example of film formation conditions, the distance between the substrate and the target is 100 mm, and the pressure is 0.6 P. a, DC power supply: 0.5 kW, film deposition atmosphere: oxygen (oxygen flow rate: 100%) In addition, when a pulsed DC power supply is used, the powdery material (particles) during film formation can be This is preferable because it can reduce the generation of dust (also called "dust" or "dust") and also reduces the variation in film thickness.

[0090] The oxide semiconductor film is processed by forming a mask of a desired shape on the oxide semiconductor film. The above mask can be used for etching the oxide semiconductor film. It can be formed by using a method such as lithography. Any method may be used to form the mask.

[0091] The oxide semiconductor film can be etched by either dry etching or wet etching. Of course, these may be used in combination.

[0092] After that, the oxide semiconductor film 106 is subjected to heat treatment to obtain a highly purified oxide semiconductor film. The oxide semiconductor film 106 is then heated to form a film 108 (see FIG. 2D). The hydrogen (including water and hydroxyl groups) is removed, the structure of the oxide semiconductor film is adjusted, and the energy gap is reduced. The temperature of the heat treatment is 250°C or higher and 650°C or higher. The temperature of the heat treatment is preferably 450° C. or higher and 600° C. or lower. It is preferable that the temperature is less than the melting point.

[0093] The heat treatment is carried out by, for example, placing the object to be treated in an electric furnace using a resistance heating element, etc., and heating the object in a nitrogen atmosphere. The oxide semiconductor film 106 is exposed to the air during this time. Avoid contact and avoid contamination with water or hydrogen.

[0094] The heat treatment device is not limited to an electric furnace, but may be a device that uses heat conduction or heat radiation from a medium such as a heated gas. For example, a device that heats the object to be treated by irradiation may be used. Rapid Thermal Anneal (GRTA) equipment, Gas Rapid Th RTA (Rapid Thermal Anneal) equipment l) The LRTA device can be used with halogen lamps, metal halide lamps, etc. lamps, xenon arc lamps, carbon arc lamps, high-pressure sodium lamps, high-pressure mercury lamps It is a device that heats the object to be treated by radiating light (electromagnetic waves) emitted from a lamp such as a The GRTA device is a device that performs heat treatment using high-temperature gas. Inert gases that do not react with the material to be treated by heat treatment, such as rare gases such as fluorine or nitrogen. is used.

[0095] For example, the heat treatment may be carried out by placing the object to be treated in a heated inert gas atmosphere for several minutes. After the heating, the object to be treated may be taken out of the inert gas atmosphere and subjected to GRTA treatment. GRTA treatment allows high-temperature heat treatment in a short time. It is possible to apply this method even under temperature conditions exceeding 100°C. During the treatment, an inert gas is used instead of oxygen. By performing heat treatment in an atmosphere containing oxygen, oxygen deficiency can be prevented. This is because it is possible to reduce defect levels in the energy gap caused by losses.

[0096] The inert gas atmosphere is nitrogen or a rare gas (helium, neon, argon) It is desirable to use an atmosphere containing, as its main component, hydrogen, water, etc. For example, nitrogen or rare gases such as helium, neon, and argon introduced into a heat treatment device are preferable. The purity of 6N (99.9999%) or more, preferably 7N (99.99999%) or more (That is, the impurity concentration is 1 ppm or less, preferably 0.1 ppm or less).

[0097] In any case, the impurities are reduced by the above heat treatment, and the semiconductor is an i-type (intrinsic) semiconductor or i-type By forming an oxide semiconductor film that is as close to the original structure as possible, a transistor with excellent characteristics can be realized. It can be realized.

[0098] The above-mentioned heat treatment has the effect of removing hydrogen, water, etc., so the heat treatment is This can also be called dehydration treatment or dehydrogenation treatment. The step of forming the oxide semiconductor film may be performed, for example, before the oxide semiconductor film is processed into an island shape. In addition, such dehydration and dehydrogenation treatments can be carried out not only once but also multiple times. good.

[0099] Next, the oxide semiconductor film 108 is subjected to treatment with oxygen 180 (oxygen doping treatment or oxygen The oxygen 180 is added to the silicon dioxide 180 through a plasma doping process (see FIG. 2(E)). It contains at least one of oxygen radicals, oxygen atoms, and oxygen ions. By performing oxygen doping treatment on the semiconductor film 108, the oxide semiconductor Oxygen is contained in the vicinity of the interface with the conductor film 108, or in the oxide semiconductor film 108 and in the vicinity of the interface. In this case, the oxygen content can be adjusted so that the stoichiometric ratio of the oxide semiconductor film 108 is More than 1x and up to 2x the stoichiometric ratio, preferably more than 1x and less than 2x Alternatively, the oxygen content is defined as the amount of oxygen in the case of a single crystal, Y, and the amount of oxygen in the case of a single crystal is defined as Y. It may be set to a degree that exceeds Y and is preferably set to 2Y. Alternatively, the oxygen content may be set to a degree that exceeds Y and is preferably set to 2Y. is calculated by taking the amount of oxygen Z in the oxide semiconductor film when oxygen doping treatment is not performed as a reference. It is also possible to exceed Z, preferably exceed Z up to 2Z. The reason why there is an upper limit to the range is that if the oxygen content is too high, the hydrogen storage alloy (hydrogen storage In the case of a silicon dioxide film (such as an alloy), the oxide semiconductor film 108 may take in hydrogen. Note that the oxygen content in the oxide semiconductor film is larger than the hydrogen content.

[0100] The crystal structure is InGaO3(ZnO) m For materials expressed as (m>0), for example, m = 1 (InGaZnO4) as a standard, InGaZnO x where x is 4 From the crystal structure of m=2 (InGaZn2O5), GaZnO x In this case, x is allowed to be more than 5 and up to 10. The excess region may be present in a part of the oxide semiconductor (including the interface).

[0101] Note that oxygen is one of the main components in the oxide semiconductor film. The oxygen concentration in the conductive film was measured by SIMS (Secondary Ion Mass Spectroscopy) It is difficult to accurately estimate the oxide semiconductor using methods such as spectroscopy. It is difficult to determine whether oxygen has been intentionally added to the conductive film.

[0102] By the way, oxygen has 17 O and 18 There are isotopes such as O, and these Their abundance ratios are known to be approximately 0.037% and 0.204% of all oxygen atoms, respectively. In other words, the concentrations of these isotopes in the oxide semiconductor film can be measured by methods such as SIMS. Therefore, by measuring these concentrations, the oxide It may be possible to estimate the oxygen concentration in the semiconductor film more accurately. By measuring the concentration, it is possible to determine whether oxygen has been intentionally added to the oxide semiconductor film. good.

[0103] for example, 18 When the concentration of O is used as a reference, the oxide semiconductor film containing oxygen The concentration of oxygen isotopes in the region D1( 18 O) and in the region where no oxygen is added The concentration of oxygen isotopes D2( 18 O) and D1( 18 O)>D2( 18 O) is completed It can be said that it stands up.

[0104] In addition, at least a part of the oxygen 180 added to the oxide semiconductor film is present in the oxide semiconductor. It is preferable that the dangling bonds are present in the film. This is because it can bond with hydrogen atoms and fix the hydrogen (immobile ionization).

[0105] The above-mentioned oxygen 180 can be generated by a plasma generator or an ozone generator. More specifically, for example, an etching process can be performed on a semiconductor device. A device capable of ashing resist masks is used to 80 can be generated to treat the oxide semiconductor film 108.

[0106] In order to more effectively add oxygen, an electrical bias is applied to the substrate. It is desirable.

[0107] The oxide semiconductor film 108 that has been subjected to the oxygen doping treatment is subjected to heat treatment (at a temperature of 150° C. to 470° C.). By the heat treatment, oxygen or the oxide semiconductor material reacts with hydrogen. By this, generated water, hydroxide, and the like can be removed from the oxide semiconductor film. Heat treatment is carried out in nitrogen, oxygen, and ultra-dry air (CRDS (cabinet)) where water and hydrogen are sufficiently reduced. The moisture content measured using a dew point meter (tilling down laser spectroscopy) is 20p pm (-55°C dew point equivalent) or less, preferably 1 ppm or less, preferably 10 ppb or less The reaction can be carried out under an atmosphere of oxygen (air), rare gas (argon, helium, etc.), etc. The doping treatment and the heat treatment may be repeated. The reliability of the transistor can be further improved. It is possible.

[0108] Next, a semiconductor layer 104 is formed in contact with a part of the oxide semiconductor film 108 and connected to the source electrode 104a and the drain electrode 104b. A gate insulating film 110 is formed to cover the electrode 104b (see FIG. 2(F)).

[0109] The gate insulating film 110 can be formed in the same manner as the insulating film 102. The insulating film 110 is made of silicon oxide, silicon nitride, aluminum oxide, or aluminum nitride. , gallium oxide, a mixture of these materials, etc. Considering that it functions as a gate insulating film for the semiconductor device, hafnium oxide, tantalum oxide, and Yttrium hafnium silicate (HfSi x O y (x>0, y>0)), nitrogen is added Added hafnium silicate (HfSi x O y (x>0, y>0)), nitrogen is added Hafnium aluminate (HfAl x O y (x>0, y>0)), etc., with high relative permittivity A new material may be used.

[0110] In addition, a laminated structure may be employed, similar to the insulating film 102. In this case, the oxide semiconductor A membrane (hereinafter referred to as membrane a) is made of an insulating material with the same components as the body membrane, and a membrane (hereinafter referred to as membrane a) is made of a material different from the component material of membrane a. It is more preferable to use a laminated structure with a film containing an oxide semiconductor (hereinafter referred to as film b). By forming a structure in which the layers are stacked in order from the film side, the charge is preferentially transferred to the charge capture center at the interface between film a and film b. Since the oxide semiconductor film is first trapped at the interface between the oxide semiconductor film and film a, This makes it possible to sufficiently suppress charge trapping on the surface, thereby improving the reliability of semiconductor devices. This is because.

[0111] Such a laminated structure may include a laminated structure of a gallium oxide film and a silicon oxide film, A laminated structure of a gallium oxide film and a silicon nitride film can be applied.

[0112] After the gate insulating film 110 is formed, it is desirable to perform a heat treatment. The temperature is 250°C or higher and 700°C or lower, preferably 450°C or higher and 600°C or lower. The temperature of the heat treatment is preferably below the strain point of the substrate.

[0113] The heat treatment is carried out in a gas atmosphere containing nitrogen, oxygen, or ultra-dry air (water content of 20 ppm or less, preferably 1 ppm or less, preferably 10 ppb or less of air), or noble gases (argon, helium, etc. The reaction may be carried out under an atmosphere of nitrogen, oxygen, ultra-dry air, or a rare gas. It is preferable that the gas does not contain water, hydrogen, etc. The purity of the element or rare gas is 6N (99.9999%) or more (i.e., impurity concentration is 1 ppm) It is preferable that the impurity concentration is 7N (99.99999%) or more (i.e., the impurity concentration is 0.1 ppm or less) is more preferable.

[0114] In the heat treatment according to this embodiment, the oxide semiconductor film 108 and the gate insulating film 110 and is heated in contact with each other. Oxygen, which may be reduced due to a chemical reaction, can be supplied to the oxide semiconductor film 108. In this sense, the heat treatment can also be called oxidation (oxygenation). .

[0115] Note that the heat treatment for oxidation is performed after the oxide semiconductor film 108 is formed. For example, after forming the gate electrode, a heat treatment for the purpose of adding oxidation is performed. Alternatively, a heat treatment for dehydration or the like may be followed by a heat treatment for oxidation. Alternatively, the heat treatment for dehydration or the like may be combined with the heat treatment for oxidation. Alternatively, the heat treatment for the purpose of oxidation may also be used for the purpose of dehydration.

[0116] As mentioned above, there are two types of treatments: heat treatment for dehydration and oxygen doping or oxidation. By applying the heat treatment, the oxide semiconductor film 108 can be formed so as to contain as few impurities as possible. The purified oxide semiconductor film 108 can be highly purified. There are very few (close to zero) carriers.

[0117] Thereafter, the gate electrode 112 is formed (see FIG. 2(G)). Butane, titanium, tantalum, tungsten, aluminum, copper, neodymium, scandium The metal material may be a metal material such as fluorine or an alloy material containing the metal material as a main component. The gate electrode 112 may have a single layer structure or a stacked layer structure.

[0118] After the gate electrode 112 is formed, an insulating film may be formed. For example, silicon oxide, silicon nitride, aluminum oxide, aluminum nitride, gallium oxide In particular, the insulating film can be formed using silicon nitride. When a com membrane is used, it is possible to prevent the added oxygen from being released to the outside, and also to prevent the oxygen from being released to the outside. This is preferable because it can effectively prevent hydrogen and the like from entering the compound semiconductor film 108 from the outside. In addition, the source electrode 104a, the drain electrode 104b, the gate electrode 112, etc. A connecting wiring may be formed.

[0119] Through the above steps, the transistor 120 is formed.

[0120] Note that the above description is based on the assumption that the oxide semiconductor film 108 which has been processed into an island shape and highly purified is treated with an acid. Although the present invention is not limited to the above example, it is possible to perform the element doping treatment. For example, after the purification and oxygen doping treatment, the oxide semiconductor film is processed into an island shape. Alternatively, oxygen doping may be performed after forming the source electrode 104a and the drain electrode 104b. Processing may be performed.

[0121] <Modification of the semiconductor device> 3A to 3D show transistors as modifications of the transistor 120 shown in FIG. Transistor 130, transistor 140, transistor 150, and transistor 160 A cross-sectional view of the above is shown.

[0122] The transistor 130 shown in FIG. 3A includes an insulating film 102, a source electrode 104a, a drain electrode 104b, and a The gate electrode 104b includes an oxide semiconductor film 108, a gate insulating film 110, and a gate electrode 112. The transistor 130 and the transistor 120 have the same configuration. The difference between them is whether or not an insulating film 114 covering the above-mentioned components is present. 30 has an insulating film 114. Other components are the same as those of the transistor 1 in FIG. 20, so for details, please refer to the description of FIG. 1.

[0123] The transistor 140 shown in FIG. 3B is different from the transistor shown in FIG. 1 in that it includes the above-described components. The transistor 140 has the same structure as the transistor 120. The difference between the transistor 140 and the transistor 120 is , the stacking order of the source electrode 104a, the drain electrode 104b, and the oxide semiconductor film 108 That is, in the transistor 120, the source electrode 104a and the drain electrode 104b are In the transistor 140, the oxide semiconductor film 108 is formed first. The other components are the same as those in Figure 1. As in 130, a structure including an insulating film 114 may be used.

[0124] The transistor 150 shown in FIG. 3C is different from the transistor shown in FIG. 1 in that it includes the above-described components. The transistor 150 has the same structure as the transistor 120. The difference between the transistor 150 and the transistor 120 is , which are located in the insulating film on the substrate 100 side. The other components are the same as those in FIG. is.

[0125] In this way, by using a laminated structure of the insulating film 102a and the insulating film 102b, the electric charge is insulated. Since the charge is preferentially trapped at the charge trapping center at the interface between the insulating film 102a and the insulating film 102b, the oxidation Therefore, charge trapping at the interface of the semiconductor film 108 can be sufficiently suppressed. The reliability of the device is improved.

[0126] The insulating film 102b is made of an insulating material containing the same components as those of the oxide semiconductor film 108. However, it is desirable that the insulating film 102a is a film containing a material different from the component material of the insulating film 102b. For example, the oxide semiconductor film 108 is preferably made of an In-Ga-Zn-based oxide semiconductor material. In this case, the insulating material with the same composition is gallium oxide. In this case, a laminated structure of a gallium oxide film and a silicon oxide film, or a laminated structure of a gallium oxide film and a silicon nitride film, A laminated structure of the above can be applied.

[0127] The transistor 160 shown in FIG. 3D is different from the transistor shown in FIG. 1 in that it includes the above-described components. The transistor 160 has the same structure as the transistor 120. The difference between the transistor 160 and the transistor 120 is , are in the insulating film on the substrate 100 side and the gate insulating film. The insulating film 102a and the insulating film 102b are laminated together, and the gate insulating film 110a and the gate The other components are the same as those in FIG. be.

[0128] In this way, the insulating film 102a and the insulating film 102b are laminated, and the gate insulating film 110a By using a laminated structure of the insulating film 102a and the gate insulating film 110b, the charges are 02b and the interface between the gate insulating film 110a and the gate insulating film 110b. Therefore, charge trapping at the interface of the oxide semiconductor film 108 can be sufficiently suppressed. This improves the reliability of the semiconductor device.

[0129] Note that the insulating film 102b and the gate insulating film 110a (that is, the film in contact with the oxide semiconductor film 108) The insulating film 108 is made of an insulating material containing the same kind of component as the oxide semiconductor film 108. The insulating film 102a and the gate insulating film 110b are made of the same material as the insulating film 102b and the gate insulating film 110a. For example, the oxide semiconductor film 108 is preferably a film containing an In-G When it is made of α-Zn oxide semiconductor material, it is possible to use insulating material made of the same kind of component. In this case, the layered structure of the gallium oxide film and the silicon oxide film is Alternatively, a laminated structure of a gallium oxide film and a silicon nitride film can be applied.

[0130] The transistor according to this embodiment is formed by heat treatment, and hydrogen, water, hydroxyl groups, or hydrogenated impurities containing hydrogen atoms, such as hydrogen compounds (also called hydrogen compounds), are removed from the oxide semiconductor; and By supplying oxygen, which may be reduced in the impurity removal process, high purity is achieved. The oxide semiconductor film is made to be i-type (intrinsic). A transistor including an oxide semiconductor film has suppressed fluctuations in electrical characteristics such as threshold voltage. It is electrically stable.

[0131] In particular, by increasing the oxygen content in the oxide semiconductor film by oxygen doping treatment, Suppresses degradation caused by electrical bias stress and thermal stress, and reduces degradation caused by light It is possible.

[0132] As described above, one embodiment of the disclosed invention provides a highly reliable transistor. It is possible.

[0133] As described above, the configurations, methods, etc. shown in this embodiment may be different from the configurations, methods, etc. shown in other embodiments. They can be used in appropriate combinations.

[0134] (Embodiment 2) In this embodiment mode, another example of a method for manufacturing a semiconductor device will be described with reference to FIGS. explain.

[0135] <Configuration Example of Semiconductor Device> The structure of the semiconductor device manufactured by the manufacturing method of this embodiment is the same as that of the transistor of the previous embodiment. The same applies to the transistor 120. That is, the insulating film 102 on the substrate 100, the source electrode 104 a, drain electrode 104b, oxide semiconductor film 108, gate insulating film 110, gate electrode 1 12 (see Figure 1).

[0136] As described in the above embodiment, in the transistor 120, the oxide semiconductor film 1 Reference numeral 08 denotes an oxide semiconductor film to which oxygen doping treatment has been performed. The insulating film 102 and the gate insulating film 110 are also subjected to oxygen doping treatment. Such an oxygen doping process results in a more reliable transistor 120. Note that, similarly to the above embodiment, a transistor with a modified structure can also be manufactured. (See FIGS. 3(A) to 3(D)).

[0137] <Example of a manufacturing process for a semiconductor device> An example of a manufacturing process of the above-described semiconductor device will be described below with reference to FIGS.

[0138] First, an insulating film 102 is formed on a substrate 100 (see FIG. 4(A)).

[0139] There is no particular restriction on the material of the substrate 100, but it should be at least durable enough to withstand the subsequent heat treatment. For example, glass substrates, ceramic substrates, quartz substrates, A sapphire substrate or the like can be used as the substrate 100. In addition, silicon or silicon carbide Single crystal semiconductor substrates such as silicon, polycrystalline semiconductor substrates, compounds such as silicon germanium It is also possible to apply a semiconductor substrate, an SOI substrate, etc., and a semiconductor element is formed on these substrates. may be used as the substrate 100.

[0140] A flexible substrate may be used as the substrate 100. When providing the transistor, the transistor may be directly formed on the flexible substrate, or the transistor may be formed on another substrate. After the transistor is formed, it may be peeled off and transferred to a flexible substrate. In order to peel off the transistor and transfer it to a flexible substrate, a peeling It is advisable to form a separation layer.

[0141] The insulating film 102 is an insulating film that functions as a base. Specifically, the insulating film 102 includes: Silicon oxide, silicon nitride, aluminum oxide, aluminum nitride, gallium oxide, The insulating film 102 may be an insulating film containing any of the above materials. The film may have a single layer structure or a laminated structure.

[0142] There is no particular limitation on the method for producing the insulating film 102. For example, plasma CVD or sputtering may be used. The insulating film 102 can be formed by a deposition method such as a deposition method using hydrogen, water, etc. The sputtering method is preferable in that it is less likely to be mixed with other metals.

[0143] The insulating film 102 is made of an insulating material containing the same components as the oxide semiconductor film to be formed later. It is particularly preferable to use such a material. Such a material is compatible with the oxide semiconductor film and can insulate the oxide semiconductor film. By using the film 102, the state of the interface with the oxide semiconductor film can be kept good. Here, the term "component of the same kind as the oxide semiconductor film" refers to a component element of the oxide semiconductor film. For example, the oxide semiconductor film may be an In-Ga-Zn When the material is composed of oxide semiconductor materials, the insulating material made of the same kind of components is oxide. Gallium, etc.

[0144] In addition, when the insulating film 102 has a stacked structure, the insulating film 102 should be made of the same material as the oxide semiconductor film. A membrane made of a different material (hereinafter referred to as membrane a) and a membrane containing a different material from the component material of membrane a (hereinafter referred to as membrane b) ) is preferably a stacked structure. By doing so, the charges are preferentially captured by the charge capture centers at the interface between film a and film b (oxide (Comparison with the interface between the semiconductor film and film a) Therefore, charge trapping at the interface of the oxide semiconductor film is sufficiently suppressed. This is because it is possible to control the temperature and improve the reliability of the semiconductor device.

[0145] Such a laminated structure may include a laminated structure of a gallium oxide film and a silicon oxide film, A laminated structure of a gallium oxide film and a silicon nitride film can be applied.

[0146] Next, the insulating film 102 is subjected to a treatment with oxygen 180a (oxygen doping treatment, oxygen plating treatment, etc.). The oxygen 180a is subjected to a process called Zuma doping (see FIG. 4(B)). The insulating film 102 contains oxygen radicals, oxygen atoms, or oxygen ions. By performing the doping treatment, oxygen can be contained in the insulating film 102, and the insulating film 102 can be formed later. In the oxide semiconductor film 108 to be formed, Oxygen can be contained in the film 108 and in the vicinity of the interface. The oxygen content in the insulating film 102 is preferably greater than the stoichiometric ratio of the insulating film 102, more preferably less than the stoichiometric ratio of the insulating film 102. More than 1 to 4 times (greater than 1 but less than 4 times), more preferably more than 1 to 2 The oxygen content is up to 1x (more than 1x but less than 2x) of that in the case of a single crystal. The amount of oxygen may be set to Y, and may exceed Y, preferably exceed Y up to 4Y. Alternatively, the oxygen content can be calculated by dividing the amount of oxygen in the insulating film without oxygen doping treatment by Z Based on this, it may be greater than Z, preferably greater than Z up to 4Z.

[0147] For example, the composition is GaO x When using gallium oxide expressed as (x>0), the single crystal Gallium oxide is Ga2O3, so x is greater than 1.5 and up to 6 (i.e., 1.5 of Ga). For example, the composition of SiO x Expressed as (x>0) When using silicon oxide, SiO2 (i.e., O is twice as much as Si), x is More than 2 and up to 8 (i.e. more than 2 times and up to 8 times Si) are allowed. Such an oxygen excess region may be present in a part of the insulating film (including the interface).

[0148] In addition, at least a part of the oxygen 180a added to the insulating film is supplied to the oxide semiconductor. After the oxidation, it is preferable that dangling bonds are present in the oxide semiconductor. This allows the hydrogen to bond with hydrogen that may remain in the film and fix the hydrogen (immobile ionization). This is because it is possible.

[0149] The oxygen 180a can be generated by a plasma generator or an ozone generator. More specifically, for example, an etching process can be performed on a semiconductor device. The oxygen is used in equipment that can perform ashing on resist masks. The insulating film 102 can be treated by generating the film 180a.

[0150] In order to more effectively add oxygen, an electrical bias is applied to the substrate. It is desirable.

[0151] Next, a source electrode and a drain electrode (formed in the same layer as this) are formed on the insulating film 102. A conductive film for forming a source electrode 1 is formed by processing the conductive film. Then, a gate electrode 104a and a drain electrode 104b are formed (see FIG. 4(C)). The distance between the end of the source electrode 104a and the end of the drain electrode 104b determines the The channel length L of the transistor is determined.

[0152] The conductive film used for the source electrode 104a and the drain electrode 104b is, for example, a metal film containing an element selected from the group consisting of I, Cr, Cu, Ta, Ti, Mo, and W, or the above-mentioned Metal nitride films containing elements (titanium nitride film, molybdenum nitride film, tungsten nitride film) ) and the like. In addition, Ti, Cu, etc. are used on either the upper or lower side of the metal film or both sides. High-melting metal films such as Mo and W, or metal nitride films (titanium nitride film, molybdenum nitride film, etc.) Alternatively, a conductive film in which a tungsten nitride film, a tungsten nitride film, or the like is stacked may be used.

[0153] The conductive film used for the source electrode 104a and the drain electrode 104b is a conductive gold film. It may be formed of a metal oxide. An example of a conductive metal oxide is indium oxide (In2O3). , tin oxide (SnO2), zinc oxide (ZnO), indium oxide tin oxide alloy (In2O 3-SnO2, abbreviated as ITO), indium oxide zinc oxide alloy (In2O3-ZnO ) or a material obtained by adding silicon oxide to these metal oxide materials can be used.

[0154] The conductive film can be processed by etching using a resist mask. The exposure to light when forming the resist mask used for etching is ultraviolet light, KrF laser light, or ArF It is advisable to use a laser beam or the like.

[0155] When performing exposure with a channel length L of less than 25 nm, for example, several nm to several tens of nm Using extreme ultraviolet light with an extremely short wavelength of 1000m, It is recommended to perform exposure when forming a resist mask. Exposure with extreme ultraviolet light has high resolution and focal depth. Therefore, the channel length L of the transistor to be formed later can be reduced. This makes it possible to increase the operating speed of the circuit.

[0156] In addition, etching is performed using a resist mask formed by a so-called multi-tone mask. The resist mask formed using the multi-tone mask has a plurality of film thicknesses. The shape can be further changed by ashing, It can be used in multiple etching processes to process into patterns. A multi-tone mask allows for resist masks that correspond to at least two different patterns. In other words, the process can be simplified.

[0157] Next, an acid film is formed on the insulating film 102 in contact with the source electrode 104a and the drain electrode 104b. An oxide semiconductor film is formed, and the oxide semiconductor film is processed to form an island-shaped oxide semiconductor film 106. (See Figure 4(D)).

[0158] The oxide semiconductor film is preferably formed by a method that does not easily allow hydrogen, water, or the like to be mixed in. The oxide semiconductor film can be formed by a method such as sputtering. The thickness of the oxide semiconductor film is preferably 3 nm to 30 nm. For example, if the film thickness is 50 nm or more, the transistor may become normally on. This is the case.

[0159] The material used for the oxide semiconductor film is the quaternary metal oxide In-Sn-Ga-Z nO-based materials, ternary metal oxide In-Ga-Zn-O-based materials, In-Sn -Zn-O based materials, In-Al-Zn-O based materials, Sn-Ga-Zn-O based materials, Al-Ga-Zn-O based materials, Sn-Al-Zn-O based materials, and binary metal oxides Certain In-Zn-O based materials, Sn-Zn-O based materials, Al-Zn-O based materials, Zn -Mg-O based materials, Sn-Mg-O based materials, In-Mg-O based materials, In-Ga- O-based materials, In-O-based materials, Sn-O-based materials, Zn-O The above materials may contain silicon oxide. In-Ga-Zn-O materials are made of indium (In), gallium (Ga), and zinc (Z). n), and the composition ratio is not particularly important. It may contain elements other than a and Zn.

[0160] The oxide semiconductor film has the chemical formula InMO3(ZnO) m Materials expressed as (m>0) Here, M is selected from Ga, Al, Mn and Co. For example, M may be Ga, Ga and Al, Ga and and Mn, or Ga and Co, etc. can be used.

[0161] When an In-Zn-O based material is used as the oxide semiconductor film, the target to be used is The composition ratio of In:Zn is 50:1 to 1:2 in atomic ratio (converted to InO In:ZnO=25:1 to 1:4), preferably In:Zn=20:1 to 1:1 (molar ratio In terms of conversion, In2O3:ZnO=10:1 to 1:2), more preferably In:Zn=1 5:1 to 1.5:1 (converted to a molar ratio of In2O3:ZnO = 15:2 to 3:4) For example, the target used to form an In-Zn-O-based oxide semiconductor has an atomic ratio of I When n:Zn:O=X:Y:Z, Z>1.5X+Y.

[0162] In this embodiment, the oxide semiconductor film is formed using an oxide semiconductor film forming method using an In—Ga—Zn—O-based oxide semiconductor film forming method. The film is formed by sputtering using a target.

[0163] As a target for forming an In-Ga-Zn-O-based oxide semiconductor film, for example, the composition ratio and For oxide semiconductor film formation with In2O3:Ga2O3:ZnO=1:1:1 [molar ratio] It should be noted that the material and composition of the target are not limited to those described above. For example, the composition of In2O3:Ga2O3:ZnO=1:1:2 [molar ratio] A target for forming an oxide semiconductor film can also be used.

[0164] The filling rate of the oxide semiconductor film forming target is 90% or more and 100% or less, preferably 95% or less. % or more and 99.9% or less. Use a target for oxide semiconductor film formation with a high filling rate. This is because the formed oxide semiconductor film can be a dense film.

[0165] The film formation atmosphere is a rare gas (typically argon) atmosphere, an oxygen atmosphere, or a rare The oxide semiconductor film may be heated under a mixed atmosphere of hydrogen, water, hydroxyl, or the like. To prevent contamination with hydrogen, water, hydroxyl groups, hydrides, etc., It is desirable to use an atmosphere using a high-purity gas from which impurities, including fluorine, have been sufficiently removed.

[0166] Note that oxygen in the insulating film 102 is supplied to the oxide semiconductor film during the formation of the oxide semiconductor film. In this way, by adding oxygen to the insulating film 102, the oxygen may be sufficiently It is possible to form an oxide semiconductor film to which an oxide is added.

[0167] More specifically, for example, the oxide semiconductor film can be formed as follows.

[0168] First, the substrate 100 is held in a film-forming chamber maintained in a reduced pressure state, and the substrate temperature is increased to 100° C. or higher. The temperature is set to 600° C. or less, preferably 200° C. or more and 400° C. or less. By forming the oxide semiconductor film in this manner, the impurity concentration in the oxide semiconductor film can be reduced. In addition, damage to the oxide semiconductor film due to sputtering can be reduced. is.

[0169] Next, while removing the remaining moisture in the film-forming chamber, impurities containing hydrogen atoms such as hydrogen and water are removed. A sufficiently purified high purity gas is introduced, and an oxide semiconductor is deposited on the substrate 100 using the target. To remove the residual moisture in the deposition chamber, a cryostat is used as an exhaust means. Using adsorption type vacuum pumps such as pumps, ion pumps, and titanium sublimation pumps It is desirable that the exhaust means be a turbo molecular pump with a cold trap added. The film formation chamber evacuated using a cryopump may contain, for example, hydrogen molecules and water. Compounds containing hydrogen atoms such as (HO) (and more preferably compounds containing carbon atoms) Since the impurities are removed, the concentration of impurities contained in the oxide semiconductor film formed in the film formation chamber can be reduced. It can be reduced.

[0170] As an example of film formation conditions, the distance between the substrate and the target is 100 mm, and the pressure is 0.6 P. a, DC power supply: 0.5 kW, film deposition atmosphere: oxygen (oxygen flow rate: 100%) In addition, when a pulsed DC power supply is used, the powdery material (particles) during film formation can be This is preferable because it can reduce the generation of dust (also called "dust" or "dust") and also reduces the variation in film thickness.

[0171] The oxide semiconductor film is processed by forming a mask of a desired shape on the oxide semiconductor film. The above mask can be used for etching the oxide semiconductor film. It can be formed by using a method such as lithography. Any method may be used to form the mask.

[0172] The oxide semiconductor film can be etched by either dry etching or wet etching. Of course, these may be used in combination.

[0173] After that, the oxide semiconductor film 106 is subjected to heat treatment to obtain a highly purified oxide semiconductor film. The oxide semiconductor film 106 is then heated to form a film 108 (see FIG. 4E). The hydrogen (including water and hydroxyl groups) is removed, the structure of the oxide semiconductor film is adjusted, and the energy gap is reduced. In addition, this heat treatment can reduce the defect level in the insulating film 102. Oxygen may be supplied to the oxide semiconductor film. The temperature of the heat treatment is 0°C or less, preferably 450°C or more and 600°C or less. It is preferably below the strain point of the plate.

[0174] The heat treatment is carried out by, for example, placing the object to be treated in an electric furnace using a resistance heating element, etc., and heating the object in a nitrogen atmosphere. The oxide semiconductor film 106 is exposed to the air during this time. Avoid contact and avoid contamination with water or hydrogen.

[0175] The heat treatment device is not limited to an electric furnace, but may be a device that uses heat conduction or heat radiation from a medium such as a heated gas. For example, a device that heats the object to be treated by irradiation may be used. Rapid Thermal Anneal (GRTA) equipment, Gas Rapid Th RTA (Rapid Thermal Anneal) equipment l) The LRTA device can be used with halogen lamps, metal halide lamps, etc. lamps, xenon arc lamps, carbon arc lamps, high-pressure sodium lamps, high-pressure mercury lamps It is a device that heats the object to be treated by radiating light (electromagnetic waves) emitted from a lamp such as a The GRTA device is a device that performs heat treatment using high-temperature gas. Inert gases that do not react with the material to be treated by heat treatment, such as rare gases such as fluorine or nitrogen. is used.

[0176] For example, the heat treatment may be carried out by placing the object to be treated in a heated inert gas atmosphere for several minutes. After the heating, the object to be treated may be taken out of the inert gas atmosphere and subjected to GRTA treatment. GRTA treatment allows high-temperature heat treatment in a short time. It is possible to apply this method even under temperature conditions exceeding 100°C. During the treatment, an inert gas is used instead of oxygen. By performing heat treatment in an atmosphere containing oxygen, oxygen deficiency can be prevented. This is because it is possible to reduce defect levels in the energy gap caused by losses.

[0177] The inert gas atmosphere is nitrogen or a rare gas (helium, neon, argon) It is desirable to use an atmosphere containing, as its main component, hydrogen, water, etc. For example, nitrogen or rare gases such as helium, neon, and argon introduced into a heat treatment device are preferable. The purity of 6N (99.9999%) or more, preferably 7N (99.99999%) or more (That is, the impurity concentration is 1 ppm or less, preferably 0.1 ppm or less).

[0178] In any case, the impurities are reduced by the above heat treatment, and the semiconductor is an i-type (intrinsic) semiconductor or i-type By forming an oxide semiconductor film that is as close to the original structure as possible, a transistor with excellent characteristics can be realized. It can be realized.

[0179] The above-mentioned heat treatment has the effect of removing hydrogen, water, etc., so the heat treatment is This can also be called dehydration treatment or dehydrogenation treatment. The step of forming the oxide semiconductor film may be performed, for example, before the oxide semiconductor film is processed into an island shape. In addition, such dehydration and dehydrogenation treatments can be carried out not only once but also multiple times. good.

[0180] Next, the oxide semiconductor film 108 is subjected to treatment with oxygen 180b (see FIG. 4F). Oxygen 180b contains at least one of the following: oxygen radicals, oxygen atoms, and oxygen ions. By performing oxygen doping treatment on the oxide semiconductor film 108, the oxide semiconductor In the conductive film 108, near the interface with the oxide semiconductor film 108, or in the oxide semiconductor film 108 and In this case, the oxygen content is determined based on the oxide semiconductor. The amount of the stoichiometric ratio of the membrane 108 is preferably more than 1 to 2 times the stoichiometric ratio. (more than 1 time but less than 2 times). Alternatively, the oxygen content is the oxygen content of the single crystal. The amount of Y may be more than Y, preferably more than Y up to 2Y. Alternatively, the oxygen content in the oxide semiconductor film may be determined by the oxygen content in the oxide semiconductor film when oxygen doping treatment is not performed. Based on the amount Z, it may be greater than Z, preferably greater than Z up to 2Z. The reason why there is an upper limit to the above-mentioned preferable range is that if the oxygen content is too high, The oxide semiconductor film 108 absorbs hydrogen like a hydrogen absorbing alloy (hydrogen storage alloy). This is because there is a risk of it getting caught.

[0181] The crystal structure is InGaO3(ZnO) m For materials expressed as (m>0), for example, m = 1 (InGaZnO4) as a standard, InGaZnO x where x is 4 From the crystal structure of m=2 (InGaZn2O5), GaZnO x In this case, x is allowed to be more than 5 and up to 10. The excess region may be present in a part of the oxide semiconductor film (including the interface).

[0182] At least a part of the oxygen 180b added to the oxide semiconductor film is It is preferable that the dangling bonds are present in the film. This is because it can bond with available hydrogen and fix the hydrogen (non-mobile ionization).

[0183] The oxygen 180b can be generated by a plasma generator or an ozone generator. More specifically, for example, an etching process can be performed on a semiconductor device. The oxygen is used in equipment that can perform ashing on resist masks. The oxide semiconductor film 108 can be treated by generating the oxide semiconductor film 180b.

[0184] In order to more effectively add oxygen, an electrical bias is applied to the substrate. It is desirable.

[0185] The oxide semiconductor film 108 that has been subjected to the oxygen doping treatment is subjected to heat treatment (at a temperature of 150° C. to 470° C.). By the heat treatment, oxygen or the oxide semiconductor material reacts with hydrogen. By this, generated water, hydroxide, and the like can be removed from the oxide semiconductor film. Heat treatment is carried out in nitrogen, oxygen, or ultra-dry air (with a moisture content of 20ppm) with sufficient reduction of water and hydrogen. m or less, preferably 1 ppm or less, preferably 10 ppb or less), rare gases (argon The process can be performed under an atmosphere of oxygen, helium, etc. In addition, the oxygen doping process and the heat treatment can be repeated. By repeating this process, the reliability of the transistor can be further improved. The number of repetitions can be set as appropriate.

[0186] Next, a semiconductor layer 104 is formed in contact with a part of the oxide semiconductor film 108 and connected to the source electrode 104a and the drain electrode 104b. A gate insulating film 110 is formed to cover the electrode 104b (see FIG. 5(A)).

[0187] The gate insulating film 110 can be formed in the same manner as the insulating film 102. The insulating film 110 is made of silicon oxide, silicon nitride, aluminum oxide, or aluminum nitride. , gallium oxide, a mixture of these materials, etc. Considering that it functions as a gate insulating film for the semiconductor device, hafnium oxide, tantalum oxide, and Yttrium hafnium silicate (HfSi x O y (x>0, y>0)), nitrogen is added Added hafnium silicate (HfSi x O y (x>0, y>0)), nitrogen is added Hafnium aluminate (HfAl x O y (x>0, y>0)), etc., with high relative permittivity A new material may be used.

[0188] In addition, a laminated structure may be employed, similar to the insulating film 102. In this case, the oxide semiconductor A membrane (hereinafter referred to as membrane a) is made of an insulating material with the same components as the body membrane, and a membrane (hereinafter referred to as membrane a) is made of a material different from the component material of membrane a. It is more preferable to use a laminated structure with a film containing an oxide semiconductor (hereinafter referred to as film b). By forming a structure in which the layers are stacked in order from the film side, the charge is preferentially transferred to the charge capture center at the interface between film a and film b. Since the oxide semiconductor film is first trapped at the interface between the oxide semiconductor film and film a, This makes it possible to sufficiently suppress charge trapping on the surface, thereby improving the reliability of semiconductor devices. This is because.

[0189] Such a laminated structure may include a laminated structure of a gallium oxide film and a silicon oxide film, A laminated structure of a gallium oxide film and a silicon nitride film can be applied.

[0190] After the gate insulating film 110 is formed, it is desirable to perform a heat treatment. The temperature is 250°C or higher and 700°C or lower, preferably 450°C or higher and 600°C or lower. The temperature of the heat treatment is preferably below the strain point of the substrate.

[0191] The heat treatment is carried out in a gas atmosphere containing nitrogen, oxygen, or ultra-dry air (water content of 20 ppm or less, preferably 1 ppm or less, preferably 10 ppb or less of air), or noble gases (argon, helium, etc. The reaction may be carried out under an atmosphere of nitrogen, oxygen, ultra-dry air, or a rare gas. It is preferable that the gas does not contain water, hydrogen, etc. The purity of the element or rare gas is 6N (99.9999%) or more (i.e., impurity concentration is 1 ppm) It is preferable that the impurity concentration is 7N (99.99999%) or more (i.e., the impurity concentration is 0.1 ppm or less) is more preferable.

[0192] In the heat treatment according to this embodiment, the oxide semiconductor film 108 and the insulating film 102 The heating is performed while the film is in contact with the gate insulating film 110. The oxygen that may be reduced by the process (dehydrogenation) is removed from the insulating film 102 and the like. In this sense, the heat treatment can be performed by heating. It can also be called oxidation (oxygenation).

[0193] Note that the heat treatment for oxidation is performed after the oxide semiconductor film 108 is formed. For example, after forming the gate electrode, a heat treatment for the purpose of adding oxidation is performed. Alternatively, a heat treatment for dehydration or the like may be followed by a heat treatment for oxidation. Alternatively, the heat treatment for dehydration or the like may be combined with the heat treatment for oxidation. Alternatively, the heat treatment for the purpose of oxidation may also be used for the purpose of dehydration.

[0194] As mentioned above, there are two types of treatments: heat treatment for dehydration and oxygen doping or oxidation. By applying the heat treatment, the oxide semiconductor film 108 can be formed so as to minimize the amount of impurities contained therein. The highly purified oxide semiconductor film 108 contains a donor-derived oxide semiconductor. There are very few (close to zero) carriers that do this.

[0195] Next, the gate insulating film 110 is treated with oxygen 180c (see FIG. 5(B)). ) Oxygen 180c contains at least one of the following: oxygen radicals, oxygen atoms, and oxygen ions. By performing oxygen doping treatment on the gate insulating film 110, the gate insulating film 110, in the oxide semiconductor film 108, near the interface of the oxide semiconductor film 108, or in the oxide semiconductor Oxygen can be contained in the conductive film 108 and in the vicinity of the interface. The oxygen content in the insulating film 110 is preferably in excess of the stoichiometric ratio of the gate insulating film 110. More preferably, more than 1 to 4 times the stoichiometric ratio (greater than 1 but less than 4 times), , more than 1 time up to 2 times (greater than 1 time but less than 2 times). Or, the oxygen content is The amount of oxygen in the case of a single crystal is defined as Y, and the amount of oxygen is preferably more than Y, and more preferably 4Y. Alternatively, the oxygen content can be determined by the gate electrode without oxygen doping. With the amount of oxygen in the insulating film Z as the standard, the amount of oxygen in the insulating film should exceed Z, preferably exceed Z to 4Z. It can also be done as follows.

[0196] For example, the composition is GaO x When using gallium oxide expressed as (x>0), the single crystal Gallium oxide is Ga2O3, so x is greater than 1.5 and up to 6 (i.e., 1.5 of Ga). For example, the composition of SiO x Expressed as (x>0) When using silicon oxide, SiO2 (i.e., O is twice as much as Si), x is More than 2 and up to 8 (i.e. more than 2 times and up to 8 times Si) are allowed. Such an oxygen excess region may be present in a part of the insulating film (including the interface).

[0197] In addition, at least a part of the oxygen 180c added to the insulating film is supplied to the oxide semiconductor. After the oxidation, it is preferable that dangling bonds are present in the oxide semiconductor. This allows the hydrogen to bond with hydrogen that may remain in the film and fix the hydrogen (immobile ionization). This is because it is possible.

[0198] The above-mentioned oxygen 180c can be generated by a plasma generator or an ozone generator. More specifically, for example, an etching process can be performed on a semiconductor device. The oxygen is used in equipment that can perform ashing on resist masks. The gate insulating film 110 can be treated by generating 180c.

[0199] In order to more effectively add oxygen, an electrical bias is applied to the substrate. It is desirable.

[0200] After the oxygen doping treatment, a heat treatment may be carried out. A sufficient amount of oxygen can be supplied to the oxide semiconductor film. The timing of the treatment may be any time after the above-mentioned oxygen doping treatment. The doping treatment and the heat treatment may be repeated. The reliability of the transistor can be further improved. It is possible.

[0201] Thereafter, the gate electrode 112 is formed (see FIG. 5(C)). Butane, titanium, tantalum, tungsten, aluminum, copper, neodymium, scandium The metal material may be a metal material such as fluorine or an alloy material containing the metal material as a main component. The gate electrode 112 may have a single layer structure or a stacked layer structure.

[0202] After the gate electrode 112 is formed, an insulating film may be formed. For example, silicon oxide, silicon nitride, aluminum oxide, aluminum nitride, gallium oxide In particular, the insulating film can be formed using silicon nitride. When a com membrane is used, it is possible to prevent the added oxygen from being released to the outside, and also to prevent the oxygen from being released to the outside. This is preferable because it can effectively prevent hydrogen and the like from entering the compound semiconductor film 108 from the outside. In addition, the source electrode 104a, the drain electrode 104b, the gate electrode 112, etc. A connecting wiring may be formed.

[0203] Through the above steps, the transistor 120 is formed.

[0204] The above description is based on the insulating film 102, the oxide semiconductor film 108, and the gate insulating film 11. This is an example in which oxygen doping is applied to all of the 0. For example, the insulating film 102 and the oxide semiconductor film 108 may be subjected to oxygen doping treatment. Alternatively, oxygen doping treatment may be applied to the oxide semiconductor film 108 and the gate insulating film 110. may be applied.

[0205] The transistor according to this embodiment is formed by heat treatment, and hydrogen, water, hydroxyl groups, or hydrogenated impurities containing hydrogen atoms, such as hydrogen compounds (also called hydrogen compounds), are removed from the oxide semiconductor; and By supplying oxygen, which may be reduced in the impurity removal process, high purity is achieved. The oxide semiconductor film is made to be i-type (intrinsic). A transistor including an oxide semiconductor film has suppressed fluctuations in electrical characteristics such as threshold voltage. It is electrically stable.

[0206] In particular, by increasing the oxygen content in the oxide semiconductor film by oxygen doping treatment, Suppresses degradation caused by electrical bias stress and thermal stress, and reduces degradation caused by light It is possible.

[0207] As described above, one embodiment of the disclosed invention provides a highly reliable transistor. It is possible.

[0208] As described above, the configurations, methods, etc. shown in this embodiment may be different from the configurations, methods, etc. shown in other embodiments. They can be used in appropriate combinations.

[0209] (Embodiment 3) In this embodiment mode, another example of a method for manufacturing a semiconductor device will be described with reference to FIGS.

[0210] <Configuration Example of Semiconductor Device> The structure of the semiconductor device manufactured by the manufacturing method of this embodiment is the same as that of the transistor of the previous embodiment. The same applies to the transistor 120. That is, the insulating film 102 on the substrate 100, the source electrode 104 a, drain electrode 104b, oxide semiconductor film 108, gate insulating film 110, gate electrode 1 12 (see Figure 1).

[0211] As described in the above embodiment, in the transistor 120, the oxide semiconductor film 1 08 denotes an oxide semiconductor film that has been subjected to oxygen doping treatment. The insulating film 102 and the gate insulating film 110 are also subjected to oxygen doping treatment. Such an oxygen doping process results in a more reliable transistor 120. Furthermore, the oxygen doping treatment for the insulating film 102 in this embodiment is carried out by Masks 103a and 103b used to form the drain electrode 104a and the drain electrode 104b By adopting this process, the process can be simplified. It is possible to reduce the manufacturing cost. A transistor can also be manufactured (see FIGS. 3A to 3D).

[0212] <Example of a manufacturing process for a semiconductor device> An example of a manufacturing process of the above-described semiconductor device will be described below with reference to FIGS. The basic content is the same as the previous embodiment, so only the differences will be described below. Meru.

[0213] First, an insulating film 102 is formed on a substrate 100 (see FIG. 6(A)). ) should be taken into consideration.

[0214] Next, a source electrode and a drain electrode (formed in the same layer as this) are formed on the insulating film 102. A conductive film for forming the conductive layer (including the wiring) is formed, and the conductive film is then covered with a mask 103a and A source electrode 104a and a drain electrode 104b are formed by processing using a mask 103b. Then, the insulating film 102 is subjected to a treatment with oxygen 180a (oxygen doping treatment, The source electrode 104a and the source electrode 104b are doped with oxygen plasma (see FIG. 6B). For details of the process for forming the drain electrode 104b, please refer to the description of FIG. 4(C). Here, the above-mentioned oxygen doping treatment is carried out after removing the mask 103a and the mask 103b. This also serves as a removal process.

[0215] The oxygen 180a contains at least one of oxygen radicals, oxygen atoms, and oxygen ions. By performing oxygen doping treatment on the insulating film 102, oxygen is introduced into the insulating film 102. In the oxide semiconductor film 108 to be formed later, 8. Oxygen is contained in the oxide semiconductor film 108 and in the vicinity of the interface, or in the oxide semiconductor film 108 and in the vicinity of the interface. In this case, the oxygen content is preferably set to a level exceeding the stoichiometric ratio of the insulating film 102. More preferably, more than 1 to 4 times the stoichiometric ratio (greater than 1 but less than 4 times), , more than 1 time up to 2 times (greater than 1 time but less than 2 times). Or, the oxygen content is The amount of oxygen in the case of a single crystal is defined as Y, and the amount of oxygen is preferably more than Y, and more preferably 4Y. Alternatively, the oxygen content can be determined by the insulating film without oxygen doping. With the amount of oxygen in the film Z as the standard, the amount is set to exceed Z, preferably exceed Z and up to 4Z. It is also possible to do so.

[0216] For example, the composition is GaO x When using gallium oxide expressed as (x>0), the single crystal Gallium oxide is Ga2O3, so x is greater than 1.5 and up to 6 (i.e., 1.5 of Ga). For example, the composition of SiO x Expressed as (x>0) When using silicon oxide, SiO2 (i.e., O is twice as much as Si), x is More than 2 and up to 8 (i.e. more than 2 times and up to 8 times Si) are allowed. Such an oxygen excess region may be present in a part of the insulating film (including the interface).

[0217] In addition, at least a part of the oxygen 180a added to the insulating film is supplied to the oxide semiconductor. After the oxidation, it is preferable that dangling bonds are present in the oxide semiconductor. This allows the hydrogen to bond with hydrogen that may remain in the film and fix the hydrogen (immobile ionization). This is because it is possible.

[0218] The oxygen 180a can be generated by a plasma generator or an ozone generator. More specifically, for example, ashing can be performed on the resist mask. The insulating film 102 can be treated by generating oxygen 180a using an apparatus such as the above.

[0219] The mask 103a and the mask 103b are removed by the oxygen doping treatment. However, unlike the normal mask removal process, this process is intended to add oxygen. Therefore, it is desirable to apply a strong bias to the substrate.

[0220] Furthermore, the oxygen doping process creates a region in the insulating film 102 where oxygen is present at a high concentration. Specifically, the insulating film 102 is formed in a region where oxygen is present at a low concentration and a region where oxygen is present at a low concentration. The area not covered by the source electrode 104a and the drain electrode 104b is where oxygen is present at a high concentration. The region covered by the source electrode 104a and the drain electrode 104b However, this is a region where oxygen exists at low concentration.

[0221] Next, an acid film is formed on the insulating film 102 in contact with the source electrode 104a and the drain electrode 104b. and forming an oxide semiconductor film by processing the oxide semiconductor film into an island-shaped oxide semiconductor film. Then, the island-shaped oxide semiconductor film is subjected to heat treatment to form a highly purified oxide semiconductor film. The compound semiconductor film 108 is formed (see FIG. 6(C)). Please refer to the description regarding Figure 4(E).

[0222] Next, the oxide semiconductor film 108 is subjected to treatment with oxygen 180b (see FIG. 6D). For details, please refer to the description regarding FIG. 4(F).

[0223] Next, a semiconductor layer 104 is formed in contact with a part of the oxide semiconductor film 108 and connected to the source electrode 104a and the drain electrode 104b. A gate insulating film 110 is formed to cover the electrode 104b. 0 is treated with oxygen 180c (see FIG. 6(E)). Please refer to the description regarding FIG. 5(B).

[0224] Thereafter, the gate electrode 112 is formed (see FIG. 6(F)). Please refer to the description.

[0225] After the gate electrode 112 is formed, an insulating film may be formed. For example, silicon oxide, silicon nitride, aluminum oxide, aluminum nitride, gallium oxide In particular, the insulating film can be formed using silicon nitride. When a com membrane is used, it is possible to prevent the added oxygen from being released to the outside, and also to prevent the oxygen from being released to the outside. This is preferable because it can effectively prevent hydrogen and the like from entering the compound semiconductor film 108 from the outside. In addition, the source electrode 104a, the drain electrode 104b, the gate electrode 112, etc. A connecting wiring may be formed.

[0226] Through the above steps, the transistor 120 is formed.

[0227] The above description is based on the insulating film 102, the oxide semiconductor film 108, and the gate insulating film 11. This is an example in which oxygen doping is applied to all of the 0. For example, the insulating film 102 and the oxide semiconductor film 108 may be subjected to oxygen doping treatment. may be applied.

[0228] The transistor according to this embodiment is formed by heat treatment, and hydrogen, water, hydroxyl groups, or hydrogenated impurities containing hydrogen atoms, such as hydrogen compounds (also called hydrogen compounds), are removed from the oxide semiconductor; and By supplying oxygen, which may be reduced in the impurity removal process, high purity is achieved. The oxide semiconductor film is made to be i-type (intrinsic). A transistor including an oxide semiconductor film has suppressed fluctuations in electrical characteristics such as threshold voltage. It is electrically stable.

[0229] In particular, by increasing the oxygen content in the oxide semiconductor film by oxygen doping treatment, Suppresses degradation caused by electrical bias stress and thermal stress, and reduces degradation caused by light It is possible.

[0230] Furthermore, in the manufacturing method according to the present embodiment, the process is simplified, and therefore the cost involved in manufacturing is reduced. This can suppress strikes.

[0231] As described above, according to one embodiment of the disclosed invention, it is possible to reduce manufacturing costs and achieve high reliability. It is possible to provide a transistor having a high resistance.

[0232] As described above, the configurations, methods, etc. shown in this embodiment may be different from the configurations, methods, etc. shown in other embodiments. They can be used in appropriate combinations.

[0233] (Fourth embodiment) In this embodiment, a plasma device (ashing device) that can be used for oxygen doping treatment is used. This device is suitable for large glass panels of the fifth generation or later. It is more suitable for industrial use than ion implantation equipment because it can accommodate various substrates.

[0234] Figure 17(A) shows an example of a top view of a single-wafer multi-chamber equipment. Figure 17(B) shows 1 is a cross-sectional view of an example of a plasma device (also called an ashing device) for performing oxygen plasma doping. show.

[0235] The single-wafer multi-chamber equipment shown in FIG. 17(A) is a plasma equipment shown in FIG. 17(B). a substrate supply chamber 11 having three cassette ports 14 for accommodating substrates to be processed; The substrate supply chamber 13 includes a load lock chamber 12, a transfer chamber 13, etc. is transferred to a vacuum chamber 15 in the plasma device 10 via a load lock chamber 12 and a transfer chamber 13. After oxygen plasma doping is completed, the substrate is transported to the The substrate is transferred from the plasma device 10 to the substrate supply chamber 11 via the load lock chamber 12 and the transfer chamber 13. The substrate supply chamber 11 and the transport chamber 13 are equipped with a transport robot for transporting the substrates to be processed. Each of the slots is placed in a different location.

[0236] Referring to Figure 17(B), the plasma device 10 includes a vacuum chamber 15. At the top of the chamber 15, there are multiple gas outlets and an ICP coil, which is a plasma generation source. The coil 16 (inductively coupled plasma coil) is located in the center of the device.

[0237] Twelve gas outlets are arranged in the central portion of the plasma device 10 when viewed from the top. Each gas outlet is connected to a gas supply source and a gas flow path 17 for supplying oxygen gas. The gas supply source is equipped with a mass flow controller or the like, and is controlled to a desired flow rate ( Oxygen gas can be supplied to the gas flow path 17 at a flow rate of more than 0 and not more than 1000 sccm. The oxygen gas supplied from the gas supply source is blown from the gas flow path 17 through 12 gas outlets. is supplied into the vacuum chamber 15 via the

[0238] The ICP coil 16 is made up of a plurality of strip-shaped conductors arranged in a spiral. The first high frequency power supply 18 (13.56) is connected to the power supply 19 via a matching circuit for impedance adjustment. MHz) and the other end is grounded.

[0239] A substrate stage 19, which functions as a lower electrode, is placed at the bottom of the vacuum chamber. The substrate to be processed is held on the substrate stage 19 by an electrostatic chuck or the like provided on the substrate stage. The substrate stage 19 is provided with a heater and a cooler as a heating mechanism. The substrate stage is equipped with a second bias voltage application channel for the substrate. It is connected to a high frequency power supply 21 (3.2 MHz).

[0240] The vacuum chamber 15 is also provided with an exhaust port and an automatic pressure control valve 22 (Autom It is equipped with an atic pressure control valve (APC). The APC is connected to a turbo molecular pump 23, and the The APC controls the pressure inside the vacuum chamber and is connected to the dry pump 24. The molecular pump 23 and the dry pump 24 reduce the pressure inside the vacuum chamber 15 .

[0241] Next, plasma is generated in the vacuum chamber 15 shown in FIG. 17(B), and the substrate 2 to be processed is heated. The oxide semiconductor film, the base insulating film, or the gate insulating film provided in the An example of a loop is shown below.

[0242] First, the turbo molecular pump 23 and the dry pump 24 are operated to After the interior of the vacuum chamber 15 is maintained at a desired pressure, the substrate 20 to be processed is placed on the substrate stage in the vacuum chamber 15. The substrate 20 to be processed held on the substrate stage is provided with at least an oxide semiconductor. In this embodiment, the vacuum chamber 15 is provided with a conductive film or an insulating base film. The pressure in the vacuum chamber is maintained at 1.33 Pa. Oxygen gas is blown into the vacuum chamber from the gas outlet. The flow rate supplied into 15 is set to 250 sccm.

[0243] Next, high frequency power is applied from the first high frequency power supply 18 to the ICP coil 16, generating a plasma. Then, the plasma is generated for a certain period of time (30 seconds or more and 600 seconds or less). The high frequency power applied to the ICP coil 16 is maintained at 1 kW or more and 10 kW or less. In this embodiment, it is set to 6000 W. At this time, the power from the second high frequency power supply 21 to the substrate A substrate bias voltage may be applied to the stage. In this embodiment, The power used is assumed to be 1000W.

[0244] In this embodiment, the plasma is generated for 60 seconds, and then the substrate 20 is The substrate 20 is then removed from the vacuum chamber 15. In this way, the oxide semiconductor formed on the substrate 20 is The conductor film, the underlying insulating film, or the gate insulating film can be doped with oxygen plasma.

[0245] As described above, the configurations, methods, etc. shown in this embodiment may be different from the configurations, methods, etc. shown in other embodiments. They can be used in appropriate combinations.

[0246] (Embodiment 5) In this embodiment, a storage medium (memory element) is shown as an example of a semiconductor device. In this embodiment, the transistor using an oxide semiconductor described in any of Embodiments 1 to 3 is A transistor including a material other than an oxide semiconductor is formed over the same substrate.

[0247] 7A and 7B show an example of the configuration of a semiconductor device. FIG. 7A shows a cross section of the semiconductor device. 7(B) shows a plan view of the semiconductor device. It corresponds to the cross section taken along lines C1-C2 and D1-D2. An example of a circuit diagram when the device is used as a memory element is shown in Figure 7(A) and Figure 7(B). The semiconductor device shown in FIG. 2 has a transistor 240 using a first semiconductor material at the bottom. The transistor 120 described in Embodiment 1 is located in the upper portion. In this embodiment, an oxide semiconductor is used as the second semiconductor material. The semiconductor material is a semiconductor material other than an oxide semiconductor. , for example, silicon, germanium, silicon germanium, silicon carbide, or gallium. It is preferable to use a single crystal semiconductor. A transistor using such a semiconductor material can easily operate at high speed. On the other hand, transistors using oxide semiconductors can maintain charge for a long time due to their characteristics. Allows retention.

[0248] Note that in this embodiment, an example in which a storage medium is formed using the transistor 120 is described. 1, but instead of the transistor 120, the transistor shown in the first or second embodiment is used. transistor 130, transistor 140, transistor 150, and transistor 160, etc. It goes without saying that it is applicable.

[0249] The transistor 240 in FIG. 7 is a substrate comprising a semiconductor material (e.g., silicon). The channel forming region 216 provided in the 200 and the The impurity region 220 is formed by the metal compound region 224 in contact with the impurity region 220. A gate insulating film 208 is provided on the panel forming region 216, and a gate insulating film 208 is provided on the gate insulating film 208. and a gate electrode 210 formed thereon.

[0250] The substrate 200 containing a semiconductor material may be a single crystal semiconductor substrate such as silicon or silicon carbide, a multi-crystal semiconductor substrate, or a silicon carbide substrate. Crystalline semiconductor substrates, compound semiconductor substrates such as silicon germanium, SOI substrates, etc. are used Generally, an "SOI substrate" is a substrate in which a silicon semiconductor film is formed on an insulating surface. In this specification, however, it refers to a substrate having a structure in which a material other than silicon is formed on an insulating surface. In other words, the semiconductor film of the "SOI substrate" is also included. The semiconductor film is not limited to a silicon semiconductor film. In addition, the SOI substrate may be made of an insulating film such as a glass substrate. The term "internal semiconductor device" also includes a structure in which a semiconductor film is provided on a substrate via an insulating film.

[0251] An element isolation insulating film 206 is provided on the substrate 200 so as to surround the transistor 240. An insulating film 228 and an insulating film 230 are provided to cover the transistor 240. In order to achieve high integration, the transistor 240 is It is desirable to have a structure without a sidewall insulating film. When the characteristics of 0 are important, a sidewall insulating film is provided on the side surface of the gate electrode 210, An impurity region 220 including regions with different impurity concentrations may be provided.

[0252] The transistor 240 may be made of silicon, germanium, silicon germanium, or silicon carbide. The transistor 240 can be fabricated using gallium arsenide or gallium arsenide. has the feature of being capable of high-speed operation. By using the GaN-type semiconductor layer as a transistor for data readout, data can be read out at high speed.

[0253] After forming the transistor 240, but before forming the transistor 120 and the capacitor element 164 As a treatment, the insulating film 228 and the insulating film 230 are subjected to CMP treatment to form the gate electrode 210. The upper surface of the gate electrode 210 is exposed by a process other than CMP. Although it is possible to apply etching treatment to the transistor 120, To achieve this, it is desirable to make the surfaces of the insulating film 228 and the insulating film 230 as flat as possible. I wish.

[0254] Next, a conductive film is formed on the gate electrode 210, the insulating film 228, the insulating film 230, etc. The conductive film is selectively etched to form the source electrode 104a and the drain electrode 104b. do.

[0255] Conductive films are formed using PVD methods such as sputtering and CVD methods such as plasma CVD. The conductive film can be formed using Al, Cr, Cu, Ta, Use of elements selected from Ti, Mo, and W, or alloys containing the above elements. Mn, Mg, Zr, Be, Nd, Sc, or a combination of these A mixed material may also be used.

[0256] The conductive film may have a single layer structure or a laminated structure of two or more layers. Single layer structure of titanium film or titanium nitride film, single layer structure of aluminum film containing silicon, aluminum Two-layer structure with titanium film laminated on titanium nitride film, two-layer structure with titanium film laminated on titanium nitride film and a three-layer structure in which a titanium film, an aluminum film, and another titanium film are laminated. When the conductive film has a single layer structure of a titanium film or a titanium nitride film, a tapered shape is used. The advantage is that it is easy to process the source electrode 104a and the drain electrode 104b. There is a

[0257] The channel length (L) of the upper transistor 120 is determined by the distance between the source electrode 104a and the drain electrode 104b. The distance between the bottom ends of the gate electrodes 104b is determined by the distance between the bottom ends of the gate electrodes 104b. When performing exposure to form a mask used to form a transistor of less than several nanometers, It is desirable to use extreme ultraviolet light with a short wavelength of 10 nm.

[0258] Next, an oxide semiconductor film is formed to cover the source electrode 104a and the drain electrode 104b. After forming the oxide semiconductor film, the oxide semiconductor film is selectively etched to form the oxide semiconductor film 108. The oxide semiconductor film is formed using the material and the formation process described in Embodiment 1.

[0259] Next, the gate insulating film 110 is formed in contact with the oxide semiconductor film 108. 10 uses the materials and forming process shown in the first embodiment.

[0260] Next, a gate electrode is formed on the gate insulating film 110 in a region overlapping with the oxide semiconductor film 108. An electrode 112a is formed, and an electrode 112b is formed in the region overlapping with the source electrode 104a.

[0261] After the gate insulating film 110 is formed, a heat treatment is performed in an inert gas atmosphere or an oxygen atmosphere. The temperature of the heat treatment should be between 200℃ and 450℃. For example, the heating temperature is 250°C or higher and 350°C or lower in a nitrogen atmosphere. By performing the heat treatment, the electrical characteristics of the transistor can be improved. This can reduce glare.

[0262] The timing of the heat treatment for the purpose of oxidation is not limited to this. After the electrode is formed, a heat treatment may be carried out for the purpose of adding oxidation. Following the heat treatment, a heat treatment for the purpose of adding oxidation may be carried out, or a heat treatment for the purpose of dehydration, etc. The heat treatment for the purpose of oxidation may be combined with the heat treatment for the purpose of oxidation. This may also serve as a heat treatment for the purpose of curing or the like.

[0263] As mentioned above, there are two types of treatments: heat treatment for dehydration and oxygen doping or oxidation. By applying the heat treatment, the oxide semiconductor film 108 can be formed so as to minimize the amount of impurities contained therein. It can be highly purified.

[0264] The gate electrode 112a and the electrode 112b are formed by forming a conductive film on the gate insulating film 110. The conductive film can be formed by selectively etching the conductive film later.

[0265] Next, an insulating film 112 is formed on the gate insulating film 110, the gate electrode 112a, and the electrode 112b. The insulating film 151 and the insulating film 152 are formed by sputtering or the like. It can be formed by using a CVD method or the like. Also, silicon oxide, silicon oxynitride, nitride Inorganic insulating materials such as silicon oxide, hafnium oxide, aluminum oxide, and gallium oxide It can be formed using materials.

[0266] Next, the drain electrode 10 is formed on the gate insulating film 110, the insulating film 151, and the insulating film 152. An opening is formed that reaches the substrate 4b. The opening is formed by selective etching using a mask or the like. This is done by ching.

[0267] Thereafter, an electrode 154 is formed in the opening, and a wiring 1 is formed on the insulating film 152 in contact with the electrode 154. Form 56.

[0268] The electrode 154 is formed by forming a conductive film in the area including the opening using, for example, a PVD method or a CVD method. After the formation of the conductive film, a part of the conductive film is removed by a method such as etching or CMP. It can be formed by

[0269] The wiring 156 is formed by a PVD method such as a sputtering method, or a CVD method such as a plasma CVD method. After forming a conductive film using a method, the conductive film is patterned. The conductive film material was selected from Al, Cr, Cu, Ta, Ti, Mo, and W. The elements and alloys containing the above elements can be used. Mn, Mg, Zr, B It is also possible to use one of E, Nd, Sc, or a combination of these materials. is similar to the source electrode 104a or the drain electrode 104b.

[0270] As described above, the transistor 120 including the highly purified oxide semiconductor film 108 and The capacitor element 164 is completed by forming a source electrode 104a, an oxide semiconductor film 108, a gate insulating film 110, and an electrode 112b.

[0271] In the capacitor 164 shown in FIG. 7, the oxide semiconductor film 108 and the gate insulating film 110 are stacked. By doing so, sufficient insulation between the source electrode 104a and the electrode 112b is ensured. Of course, in order to ensure a sufficient capacitance, the oxide semiconductor film 108 may be provided. Furthermore, if capacitance is not required, the capacitance element 164 may be It is also possible to configure the system without providing 64.

[0272] FIG. 7C shows an example of a circuit diagram in which the semiconductor device is used as a memory element. In FIG. 7C, one of the source electrode and the drain electrode of the transistor 120, One electrode of the capacitor 164 and the gate electrode of the transistor 240 are electrically connected. In addition, the first wiring (also called the source line) and the transistor 2 The source electrode of 40 is electrically connected to the second wiring (2nd Line: bit line). The third wiring (also referred to as the third wiring) and the drain electrode of the transistor 240 are electrically connected. line (also called the 3rd Line: first signal line) and the source electrode of the transistor 120 The other of the drain electrodes is electrically connected to the fourth wiring (4th Li ne (also referred to as a second signal line) and the gate electrode of the transistor 120 are electrically connected. The fifth wiring (also called the word line) and the capacitance element The other electrode of 164 is electrically connected.

[0273] The transistor 120 including an oxide semiconductor has an extremely low off-state current. Therefore, by turning off the transistor 120, the source of the transistor 120 one of the source electrode and drain electrode of the capacitor 164, one of the electrodes of the transistor 24 The potential of the node (hereinafter referred to as node FG) electrically connected to the gate electrode of By including the capacitor element 164, This makes it easier to retain the charge given to node FG and to read out the retained information. It becomes easier.

[0274] When storing (writing) information in the semiconductor device, first, the potential of the fourth wiring is set to The transistor 120 is turned on by applying a potential to the transistor 120. As a result, the potential of the third wiring is supplied to the node FG, and a predetermined amount of charge is accumulated in the node FG. Here, the charges that give two different potential levels (hereinafter referred to as low level) are accumulated. Either a low level charge or a high level charge is given. After that, the potential of the fourth wiring is set to a potential that turns off the transistor 120. By turning off the capacitor 120, the node FG is in a floating state. As described above, a predetermined amount of charge is retained at node FG. By storing and holding the charge, information can be stored in the memory cell.

[0275] Since the off-state current of the transistor 120 is extremely small, the charge supplied to the node FG is Therefore, no refresh operation is required or This makes it possible to reduce the frequency of refresh operations significantly, thereby significantly reducing power consumption. In addition, even if there is no power supply, the memory contents can be maintained for a long period of time. It is possible to do this.

[0276] When reading out the stored information (reading), a predetermined potential (constant potential) is applied to the first wiring. In this state, when an appropriate potential (read potential) is applied to the fifth wiring, the potential is held at the node FG. Depending on the amount of charge applied, transistor 240 assumes different states. If 240 is an n-channel type, when a high-level charge is held at node FG, The apparent threshold voltage V of the transistor 240 th_H A low-level charge is applied to node FG. The apparent threshold voltage V of the transistor 240 when th_L become lower Here, the apparent threshold is the value at which the transistor 240 is turned on. Therefore, the potential of the fifth wiring is V t h_H and V th_L By setting the potential V0 between the two, the charge held in node FG is For example, if a high level charge is applied during writing, , the potential of the fifth wire is V0 (>V th_H ), transistor 240 is in the "ON" state. When a low level charge is applied, the potential of the fifth wire becomes V0( <V th_L ), transistor 240 remains in the "off state." The potential of the wiring 5 is controlled to read out the on / off state of the transistor 240 ( The stored information can be read by reading out the potential of the second wiring.

[0277] In addition, when the stored information is rewritten, a predetermined amount of data is written. By supplying a new potential to the node FG that holds the charge, new information is stored in the node FG. Specifically, the potential of the fourth wiring is set to a value that is higher than the potential of the fourth wiring when the transistor 120 is turned on. The transistor 120 is turned on by applying a potential to the third wiring. A potential (potential related to new information) is supplied to node FG, and a predetermined amount of charge is applied to node FG. After that, the potential of the fourth wiring is set to a potential that turns off the transistor 120. By turning off the transistor 120, the node FG receives the new information. That is, a predetermined amount of charge is stored in the node FG by the first write. While the charge is held, the same operation as the first write (second write) is performed. It is possible to overwrite the stored information.

[0278] The transistor 120 described in this embodiment is a highly purified and intrinsic oxide semiconductor. By using the film 108, the off-state current of the transistor 120 can be sufficiently reduced. In addition, when the oxide semiconductor film 108 is an oxygen-excess layer, the electric conductivity of the transistor 120 is improved. Fluctuations in electrical characteristics are suppressed, and an electrically stable transistor can be obtained. By using such transistors, it is possible to retain stored data for an extremely long period of time. This makes it possible to obtain a highly reliable semiconductor device.

[0279] In the semiconductor device described in this embodiment, the transistor 240 and the transistor By overlapping the layers 120, a semiconductor device with a sufficiently high degree of integration can be realized.

[0280] As described above, the configurations, methods, etc. shown in this embodiment may be different from the configurations, methods, etc. shown in other embodiments. They can be used in appropriate combinations.

[0281] (Sixth embodiment) A semiconductor device having a display function using the transistors described in any of Embodiments 1 to 3 In addition, a driving circuit including a transistor can be manufactured. A part or the whole of the circuit is formed integrally on the same substrate as the pixel section to form a system on panel. It is possible.

[0282] In FIG. 8A, a pixel portion 4002 provided on a first substrate 4001 is surrounded by a A sealant 4005 is provided thereon, and the substrate is sealed with a second substrate 4006. In (A), the area surrounded by the sealing material 4005 on the first substrate 4001 In a region different from the above, a single crystal semiconductor film or a polycrystalline semiconductor film is formed on a separately prepared substrate. A scanning line driver circuit 4004 and a signal line driver circuit 4003 are mounted. The signal line driver circuit 4003 and the scanning line driver circuit 4004 or the pixel portion 4002 are formed. The various signals and potentials are applied to the FPC (Flexible Printed Circuit) It is supplied by FPC4018a and FPC4018b.

[0283] In FIG. 8B and FIG. 8C, a pixel portion 4002 provided on a first substrate 4001 A sealant 4005 is provided so as to surround the scanning line driver circuit 4004 . In addition, a second substrate 4006 is provided on the pixel portion 4002 and the scanning line driver circuit 4004. Therefore, the pixel portion 4002 and the scanning line driver circuit 4004 are connected to the first substrate 4001. The display element is sealed by a sealant 4005 and a second substrate 4006 . In FIG. 8B and FIG. 8C, the sealing material 4005 on the first substrate 4001 In a region different from the surrounded region, a single crystal semiconductor film or a polycrystalline semiconductor film is formed on a separately prepared substrate. A signal line driver circuit 4003 formed of a crystalline semiconductor film is mounted. In C), a signal line driver circuit 4003 and a scanning line driver circuit 4004 are separately formed. Various signals and potentials given to the pixel portion 4002 are supplied from the FPC 4018. There are.

[0284] Furthermore, the embodiment is not limited to the configurations shown in FIGS. 8(A) to 8(C). Only a part of the signal line driver circuit or a part of the scanning line driver circuit may be separately formed and mounted.

[0285] The method of connecting the separately formed drive circuit is not particularly limited, and may be a COG (C Hip On Glass method, wire bonding method, or TAB (Tape On Glass) method The Automated Bonding method can be used. This is an example in which a signal line driver circuit 4003 and a scanning line driver circuit 4004 are implemented by the COG method. 8(B) shows an example in which a signal line driver circuit 4003 is mounted by the COG method. C) is an example in which the signal line driver circuit 4003 is mounted by the TAB method.

[0286] The display device includes a panel in which a display element is sealed, and a controller for the panel. This includes modules in which ICs, etc., including lasers, are mounted.

[0287] In this specification, the term "display device" refers to an image display device, a display device, or Refers to light sources (including lighting devices), and connectors such as FPC or TAB tape. Or a module with TCP attached, TAB tape or printed wiring at the end of TCP A module with a board or a display element with an IC (integrated circuit) directly mounted using the COG method All mounted modules are also included in the display device.

[0288] The pixel portion and the scanning line driver circuit provided on the first substrate include a plurality of transistors. The transistors described as examples in any of Embodiments 1 to 3 can be used. Cut.

[0289] Examples of display elements provided in the display device include liquid crystal elements (also called liquid crystal display elements), light-emitting elements, and the like. The light-emitting element can be a light-emitting display element. This category includes elements whose brightness is controlled by the light source, specifically inorganic EL (Electroluminescent) Luminescence elements, organic EL elements, etc. Also, electronic ink, etc. A display medium whose contrast changes by electrical action can also be applied.

[0290] One embodiment of a semiconductor device will be described with reference to FIGS. This corresponds to the cross-sectional view taken along line MN in FIG. 8(B).

[0291] As shown in FIGS. 9 to 11, the semiconductor device has a connection terminal electrode 4015 and a terminal electrode 40 16, and the connection terminal electrode 4015 and the terminal electrode 4016 are connected to an FPC 4018. The terminals are electrically connected to the corresponding terminals via an anisotropic conductive film 4019 .

[0292] The connection terminal electrode 4015 is formed from the same conductive film as the first electrode layer 4030. 4016 is a source electrode and a drain electrode of the transistor 4010 and the transistor 4011. It is made of the same conductive film as the electrodes.

[0293] A pixel portion 4002 and a scanning line driver circuit 4004 are provided on a first substrate 4001. 9 to 11, the transistors included in the pixel portion 4002 are 4004 and a transistor 4011 included in the scanning line driver circuit 4004. In FIG. 10 and FIG. 11, the transistors 4010 and 4011 are , an insulating layer 4021 is provided.

[0294] In this embodiment, the transistors 4010 and 4011 are The transistor described in any of Embodiments 1 to 3 can be used. The electrical characteristics of the transistor 4010 and the transistor 4011 are suppressed, and the electrical characteristics are stable. Therefore, the semiconductor device of this embodiment mode shown in FIGS. 9 to 11 has high reliability. A semiconductor device can be provided.

[0295] The transistor 4010 provided in the pixel portion 4002 is electrically connected to a display element. The display element is not particularly limited as long as it can display an image, and various display elements can be used. A child can be used.

[0296] FIG. 9 shows an example of a liquid crystal display device using a liquid crystal element as a display element. The liquid crystal element 4013 includes a first electrode layer 4030, a second electrode layer 4031, and a The liquid crystal layer 4008 is sandwiched between insulating layers that function as alignment layers. The second electrode layer 4031 is provided on the second substrate 4 The first electrode layer 4030 and the second electrode layer 4031 are disposed on the liquid crystal layer 4008 side. The structure is such that the layers are stacked via a

[0297] The columnar spacers 4035 are obtained by selectively etching the insulating film. The spacer is provided to control the film thickness (cell gap) of the layer 4008. The shape is not limited to a columnar shape, and for example, a spherical spacer may be used.

[0298] When liquid crystal elements are used as display elements, thermotropic liquid crystals, low molecular weight liquid crystals, polymer Liquid crystal, polymer dispersed liquid crystal, ferroelectric liquid crystal, antiferroelectric liquid crystal, etc. can be used. These liquid crystal materials can be in a cholesteric phase, smectic phase, cubic phase, or chromatic phase depending on the conditions. It shows an isotropic phase, an isotropic phase, etc.

[0299] Alternatively, a liquid crystal that exhibits a blue phase without using an alignment film may be used. When the temperature of the cholesteric liquid crystal is increased, the cholesteric phase transitions to the isotropic phase. The blue phase appears only in a narrow temperature range, so it is necessary to improve the temperature range. In order to improve the liquid crystal layer, a liquid crystal composition containing several weight percent or more of a chiral agent is used. The liquid crystal composition containing a liquid crystal exhibiting a monochromatic phase and a chiral agent has a short response time of 1 msec or less. Because it is optically isotropic, alignment treatment is not required and viewing angle dependency is small. Since it is not necessary to provide a surface, rubbing treatment is also unnecessary. Therefore, it is possible to prevent electrostatic breakdown, which occurs during the manufacturing process, and to reduce defects and damage to the liquid crystal display device. Therefore, it is possible to improve the productivity of the liquid crystal display device.

[0300] The specific resistivity of the liquid crystal material is 1×10 9 Ω·cm or more, preferably 1×10 11 Ω·cm or more, and more preferably 1×10 12 Ω·cm or more. The specific resistivity values ​​in the specification are values ​​measured at 20°C.

[0301] The size of the storage capacitor provided in the liquid crystal display device is determined by the It is set so that the charge can be maintained for a predetermined period, taking into consideration the break current, etc. By using a transistor with a semiconductor film, the liquid crystal capacitance in each pixel It is sufficient to provide a storage volume having a size of 1 / 3 or less, preferably 1 / 5 or less, of the capacity of the do.

[0302] The transistor including the purified oxide semiconductor film used in this embodiment has an off-state Therefore, the current value (off-state current value) in the OFF state can be reduced. The signal retention time can be extended, and the write interval can also be set longer when the power is on. Therefore, the frequency of refresh operations can be reduced, which is effective in reducing power consumption. To bear fruit.

[0303] In addition, the transistor including the purified oxide semiconductor film used in this embodiment has the following characteristics: Since a relatively high field effect mobility can be obtained, high speed driving is possible. By using such a transistor in a pixel portion of a device, a high-quality image can be provided. In addition, the transistors are separately formed in a driver circuit portion and a pixel portion on the same substrate. This allows the number of components in the liquid crystal display device to be reduced.

[0304] There are two types of LCD displays: TN (Twisted Nematic) mode, IPS (In- Plane-Switching mode, FFS (Fringe Field Switching) mode tching) mode, ASM(Axially Symmetric aligned) Micro-cell) mode, OCB(Optical Compensated) Birefringence mode, FLC (Ferroelectric Liquid Crystal id Crystal) mode, AFLC (AntiFerroelectric Li You can use modes such as quid Crystal.

[0305] In addition, normally black type liquid crystal display devices, for example, vertical alignment (VA) mode, are used. Here, the vertical alignment mode is a mode in which the liquid crystal display panel It is a type of method for controlling the arrangement of liquid crystal molecules on the panel surface when no voltage is applied. In this method, the liquid crystal molecules are oriented perpendicular to the screen. For example, MVA (Multi-Domain Vertical Alignment) ment) mode, PVA (Patterned Vertical Alignment) t) mode, ASV (Advanced Super View) mode, etc. Also, a pixel can be divided into several regions (sub-pixels), and each Multi-domain or multi-domain design, which is designed to tilt the molecule in different directions. A method called "counting" can be used.

[0306] In addition, in display devices, black matrices (light-shielding layers), polarizing members, phase difference members, reflectors, Optical members (optical substrates) such as anti-reflection members are provided as appropriate. Circularly polarized light from a differential substrate may also be used. may also be used.

[0307] In addition, multiple light-emitting diodes (LEDs) are used as backlights to display the time-division information. It is also possible to use the field sequential driving method. By applying the char drive method, color display is possible without using a color filter. It is possible.

[0308] In addition, the display method in the pixel section uses the progressive method, interlace method, etc. In addition, the color elements controlled by pixels when displaying colors are RGB (R is red, G is green, and B is blue). For example, RGBW (W is white) ), or RGB plus one or more colors such as yellow, cyan, or magenta. The size of the display area may be different for each dot of the color element. The present invention is not limited to color display devices, but can also be applied to monochrome display devices. It can also be done as follows.

[0309] In addition, a light-emitting device using electroluminescence is used as a display element included in the display device. The light-emitting element using electroluminescence can be applied to a light-emitting material. They are classified according to whether the material is an organic compound or an inorganic compound. The latter is called an inorganic EL element.

[0310] In an organic EL element, when a voltage is applied to the light-emitting element, electrons and positive electrodes are released from a pair of electrodes. The holes are then injected into a layer containing a light-emitting organic compound, allowing a current to flow. The recombination of carriers (electrons and holes) causes light-emitting organic compounds to form excited states. The excited state is formed, and light is emitted when the excited state returns to the ground state. Such a light-emitting element is called a current-excited light-emitting element.

[0311] Inorganic EL elements are classified into dispersion-type inorganic EL elements and thin-film-type inorganic EL elements depending on the element structure. Dispersion-type inorganic EL elements have a light-emitting layer in which particles of light-emitting material are dispersed in a binder. The emission mechanism is a donor- The thin-film inorganic EL element is an acceptor recombination type luminescence element. The luminescent layer is sandwiched between dielectric layers. The structure is sandwiched between electrodes, and the light emission mechanism is the inner shell electron transition of the metal ion. This is a localized light emission that utilizes organic EL elements. do.

[0312] The light emitting element only needs to have at least one of the pair of electrodes transparent in order to extract light. Then, a transistor and a light emitting element are formed on the substrate, and light is emitted from the surface opposite to the substrate. Top emission, bottom emission, and light emission from the substrate side. There are light emitting elements with a double-sided emission structure that emits light from the side, and light emitting elements with any emission structure are suitable. It can be used.

[0313] Figure 10 shows an example of a light-emitting device using a light-emitting element as a display element. The transistor 4513 is electrically connected to the transistor 4010 provided in the pixel portion 4002. The light-emitting element 4513 includes a first electrode layer 4030, an electroluminescent layer 4511, a second electrode layer 4032, a third electrode layer 4033, a fourth electrode layer 4034, a fourth electrode layer 4035, a fourth electrode layer 4036, a fourth electrode layer 4037, a fourth electrode layer 4038, a fifth electrode layer 4039, a sixth ... The light-emitting element 4513 has a stacked structure of two electrode layers 4031, but is not limited to the structure shown. The configuration of the light emitting element 4513 can be changed as needed to suit the direction of the light to be extracted. do.

[0314] The partition wall 4510 is formed using an organic insulating material or an inorganic insulating material. An opening is formed on the first electrode layer 4030 using a resin material, and the sidewall of the opening is continuous. It is preferable to form the inclined surface with a certain curvature.

[0315] The electroluminescent layer 4511 may be composed of a single layer or a plurality of layers stacked. It doesn't matter whether it is completed or not.

[0316] The second electrode is formed to prevent oxygen, hydrogen, moisture, carbon dioxide, etc. from entering the light-emitting element 4513. A protective film may be formed on the layer 4031 and the partition wall 4510. The protective film may be silicon nitride. Con film, silicon nitride oxide film, DLC (Diamond-Like Carbon) film, etc. In addition, the first substrate 4001, the second substrate 4006, and the sheet The space sealed by the sealing material 4005 is sealed with a filling material 4514. A protective film (laminating film) with high airtightness and low outgassing is used to prevent exposure to the outside air. packaging (enclosure) with a covering material (such as a protective film or ultraviolet curing resin film) is preferred.

[0317] Filler 4514 can be an inert gas such as nitrogen or argon, or an ultraviolet curing resin. Alternatively, thermosetting resins can be used, such as PVC (polyvinyl chloride), acrylic, and polyvinyl chloride. Imide, epoxy resin, silicone resin, PVB (polyvinyl butyral) or EVA (ethylene vinyl acetate) can be used. For example, nitrogen can be used as a filler. That's fine.

[0318] If necessary, a polarizing plate or a circular polarizing plate (including an elliptical polarizing plate) may be attached to the light-emitting surface of the light-emitting element. ), retardation plates (λ / 4 plate, λ / 2 plate), color filters, and other optical films are provided as needed. Alternatively, an anti-reflection film may be provided on the polarizing plate or the circular polarizing plate. This allows for anti-glare treatment to be applied, which can diffuse reflected light and reduce glare.

[0319] It is also possible to provide electronic paper that drives electronic ink as a display device. Electronic paper is also called an electrophoretic display (electrophoretic display), It has the same readability as paper, consumes less power than other display devices, and can be made thin and light. This has the advantage that:

[0320] The electrophoretic display device may have various forms, but the first particles have a positive charge. and a second particle having a negative charge are mixed with a solvent or solute. By applying an electric field to the microcapsules, By moving the particles in the capsule in opposite directions, only the color of the particles that have gathered on one side is displayed. The first particles or the second particles contain a dye, and in the absence of an electric field, The first particle and the second particle are different in color (including colorless). (Mm).

[0321] In this way, electrophoretic displays are designed so that materials with high dielectric constants move to areas with high electric fields. This is a display that utilizes the so-called dielectrophoretic effect.

[0322] The microcapsules dispersed in a solvent are called electronic ink. This electronic ink can be printed on surfaces such as glass, plastic, fabric, and paper. Furthermore, color display is possible by using color filters or particles containing pigments.

[0323] The first particles and the second particles in the microcapsules are made of a conductive material and an insulating material. , semiconductor materials, magnetic materials, liquid crystal materials, ferroelectric materials, electroluminescent materials, A material selected from the group consisting of electrochromic materials, magnetophoretic materials, and composite materials of these. Just use

[0324] In addition, a display device using a twist ball display method can also be applied as electronic paper. The twist ball display method uses spherical particles painted in black and white as the display element. The electrode layer is disposed between the first electrode layer and the second electrode layer. Display is achieved by controlling the orientation of the spherical particles by applying a potential difference to the second electrode layer. It is a method.

[0325] FIG. 11 shows an active matrix electronic paper as one mode of a semiconductor device. The electronic paper in FIG. 11 is an example of a display device that uses a twisting ball display method.

[0326] A first electrode layer 4030 connected to the transistor 4010 and a second electrode layer 4031 provided on the second substrate 4006 A black region 4615a and a white region 4615b are formed between the second electrode layer 4031 and the A spherical particle 4613 is provided, which has a cavity 4612 filled with liquid around it. The spherical particles 4613 are filled with a filler 4614 such as resin. The electrode layer 4031 corresponds to a common electrode (opposite electrode). It is electrically connected to the wire.

[0327] 9 to 11, the first substrate 4001 and the second substrate 4006 are In addition to a glass substrate, a flexible substrate can also be used. For example, a transparent plastic substrate can be used. As for plastic, FRP (Fibre Reinforced Plastic) can be used. Glass-Reinforced Plastics) board, PVF (Polyvinyl Fluorocarbon A metal film, polyester film or acrylic resin film can be used. In addition, aluminum foil is sandwiched between PVF film or polyester film. Sheets can also be used.

[0328] The insulating layer 4021 can be formed using an inorganic insulating material or an organic insulating material. In addition, acrylic resin, polyimide, benzocyclobutene resin, polyamide, epoxy resin The use of a heat-resistant organic insulating material such as grease is suitable for the planarizing insulating film. In addition to the above organic insulating materials, low-k materials, siloxane resins, PS G (phosphorus glass), BPSG (boron phosphorus glass), etc. can be used. The insulating layer may be formed by stacking a plurality of insulating films made of these materials.

[0329] The method for forming the insulating layer 4021 is not particularly limited, and may be a sputtering method, Spin coating, dipping, spray coating, droplet ejection method (inkjet method, etc.), Screen printing, offset printing, etc. can be applied. Roll coating, car The insulating layer 4021 can also be formed by using ten-coating, knife coating, etc. do.

[0330] A display device transmits light from a light source or a display element to display an image. The thin films such as the substrate, insulating film, and conductive film provided in the pixel area are all in the visible light wavelength range. It is translucent to

[0331] A first electrode layer and a second electrode layer (a pixel electrode layer and a common electrode layer) that apply a voltage to the display element , counter electrode layer, etc.), the direction of the light to be extracted, the location of the electrode layer, The light transmission property or reflectivity can be selected depending on the pattern structure of the electrode layer.

[0332] The first electrode layer 4030 and the second electrode layer 4031 are made of indium containing tungsten oxide. oxide, indium zinc oxide with tungsten oxide, indium oxide with titanium oxide oxide, indium tin oxide containing titanium oxide, indium tin oxide (hereinafter referred to as ITO) ), indium zinc oxide, indium tin oxide doped with silicon oxide, etc. A conductive material having such a property can be used.

[0333] The first electrode layer 4030 and the second electrode layer 4031 are made of tungsten (W) and molybdenum (Mo). Mo, Zirconium (Zr), Hafnium (Hf), Vanadium (V), Niobium ( Nb), Tantalum (Ta), Chromium (Cr), Cobalt (Co), Nickel (Ni), Metals such as tungsten (Ti), platinum (Pt), aluminum (Al), copper (Cu), and silver (Ag) or its alloy or nitride thereof. can.

[0334] In addition, since transistors are easily damaged by static electricity, etc., a protective circuit for protecting the drive circuit is It is preferable to provide a path. The protection circuit is preferably constructed using a non-linear element.

[0335] As described above, the transistors exemplified in any of Embodiments 1 to 3 can be used. As a result, a highly reliable semiconductor device can be provided.

[0336] This embodiment mode can be implemented by being appropriately combined with the configurations described in other embodiment modes. It is Noh.

[0337] (Embodiment 7) The transistor exemplified in any one of the first to third embodiments is used to A semiconductor device having an image sensor function for reading information about an object can be manufactured.

[0338] FIG. 12A shows an example of a semiconductor device having an image sensor function. 12(B) is a cross-sectional view showing a part of the photosensor. do.

[0339] The photodiode 602 has one electrode connected to a photodiode reset signal line 658, The other electrode is electrically connected to the gate of transistor 640. 0 indicates that either the source or the drain is connected to the photosensor reference signal line 672. The other of the drains is electrically connected to one of the source and drain of the transistor 656. The transistor 656 has a gate connected to a gate signal line 659 and a source or drain connected to a The other end is electrically connected to a photosensor output signal line 671 .

[0340] Note that in the circuit diagrams in this specification, a transistor including an oxide semiconductor film is not clearly shown. In order to make it clear, the symbol for a transistor using an oxide semiconductor film is denoted by “OS.” In FIG. 12A, the transistor 640 and the transistor 656 are oxide semiconductors. It is a transistor that uses a thin film.

[0341] FIG. 12B shows a photodiode 602 and a transistor 603 in the photosensor. 40, a substrate 601 (TFT substrate) having an insulating surface is provided with a sensor. A photodiode 602 and a transistor 640 are provided to function as a photodiode. A substrate 613 is provided on the diode 602 and the transistor 640 using an adhesive layer 608. An insulating film 631, a first interlayer insulating layer 633, a A second interlayer insulating layer 634 is provided.

[0342] Also, the gate electrode of the transistor 640 is electrically connected to the gate electrode of the transistor 640. A gate electrode 645 is provided in the same layer. The first interlayer insulating layer 633 is electrically connected to the electrode layer 641 through an opening formed therein. The electrode layer 641 is electrically connected to a conductive layer 643 formed on the second interlayer insulating layer 634. However, the electrode layer 642 is electrically connected to the gate electrode 645 via the electrode layer 644. The photodiode 602 is electrically connected to a transistor 640 .

[0343] The photodiode 602 is provided on the first interlayer insulating layer 633. Electrode layer 641 formed on 633 and electrode layer 64 provided on second interlayer insulating layer 634. 2, a first semiconductor layer 606a, a second semiconductor layer 606b, and a The semiconductor layer 606 has a laminated structure of a first semiconductor layer 606b and a second semiconductor layer 606c.

[0344] In this embodiment, the transistor 640 is the transistor according to any one of Embodiments 1 to 3. The transistors shown in the figures can be applied to the transistor 640 and the transistor 656 has suppressed fluctuations in electrical characteristics and is electrically stable, so it is suitable for the main As the semiconductor device of the embodiment, a highly reliable semiconductor device can be provided.

[0345] Here, the first semiconductor layer 606a is a semiconductor layer having a p-type conductivity, and the second semiconductor layer The layer 606b is a high-resistance semiconductor layer (i-type semiconductor layer), and the third semiconductor layer 606c is an n-type 1 shows a pin-type photodiode in which semiconductor layers having the above conductivity types are stacked.

[0346] The first semiconductor layer 606a is a p-type semiconductor layer, and is made of an amorphous material containing an impurity element that imparts p-type conductivity. The first semiconductor layer 606a can be formed of a thick silicon film. The plasma CVD method uses semiconductor material gas containing impurity elements (e.g., boron (B)). Silane (SiH4) may be used as the semiconductor material gas. Si2H6, SiH2Cl2, SiHCl3, SiCl4, SiF4, etc. may also be used. In addition, after forming an amorphous silicon film that does not contain impurity elements, An impurity element may be introduced into the amorphous silicon film by an ion implantation method. After the impurity element is introduced by the method, the impurity element may be diffused by heating or the like. In this case, the amorphous silicon film can be formed by LPCVD or vapor phase growth. Alternatively, sputtering or the like may be used. The thickness of the first semiconductor layer 606a is 10 nm or more. It is preferable to form it so that the upper limit is 50 nm or less.

[0347] The second semiconductor layer 606b is an i-type semiconductor layer (intrinsic semiconductor layer) and is made of amorphous silicon. The second semiconductor layer 606b is formed by an ammonia film using a semiconductor material gas. The silicon film is formed by the plasma CVD method. Alternatively, Si2H6, SiH2Cl2, SiHCl3, The second semiconductor layer 606b may be formed by the LPCVD method. The second semiconductor layer 606b may be formed by vapor deposition, sputtering, or the like. It is preferable to form it so that the thickness is 200 nm or more and 1000 nm or less.

[0348] The third semiconductor layer 606c is an n-type semiconductor layer and is made of an aluminium containing an impurity element that imparts n-type conductivity. The third semiconductor layer 606c is formed of a ruthenium silicon film. Formed by plasma CVD using semiconductor material gas containing elements (e.g., phosphorus (P)) Silane (SiH4) can be used as the semiconductor material gas. , SiH2Cl2, SiHCl3, SiCl4, SiF4, etc. may also be used. After forming an amorphous silicon film that does not contain any organic elements, the film is then formed by using a diffusion method or ion implantation method. Impurity elements may be introduced into the amorphous silicon film by ion implantation or the like. After the impurity element is introduced, the impurity element may be diffused by heating or the like. The amorphous silicon film can be formed by LPCVD, vapor phase growth, or silicon dioxide. The third semiconductor layer 606c may be formed by sputtering or the like. It is preferable to form it so that the thickness is m or less.

[0349] The first semiconductor layer 606a, the second semiconductor layer 606b, and the third semiconductor layer 606c are Instead of an amorphous semiconductor, a polycrystalline semiconductor may be used. (Semi-amorphous Semiconductor r:SAS)) may also be used.

[0350] Considering the Gibbs free energy, microcrystalline semiconductors are in a quasi-stable state intermediate between amorphous and single crystal. In other words, it is a semiconductor that has a third thermodynamically stable state. Therefore, it has short-range order and lattice distortion. Microcrystalline silicon, a typical example of a microcrystalline semiconductor, grows in the normal direction. The spectrum of single crystal silicon is 520 cm -1 It is shifted to the lower wavenumber side. 520cm, which indicates single crystal silicon -1 and 480 cm, which indicates amorphous silicon -1 The Raman spectrum of microcrystalline silicon has a peak between these two. To terminate the group, hydrogen or halogen is contained at least 1 atomic % or more. Furthermore, rare gas elements such as helium, neon, argon, and krypton are added to reduce lattice distortion. By further promoting the crystallization, the stability is increased and a good microcrystalline semiconductor film can be obtained.

[0351] This microcrystalline semiconductor film is produced by a high-frequency plasma CVD method with a frequency of several tens to several hundreds of MHz. Alternatively, it can be formed by a microwave plasma CVD apparatus with a frequency of 1 GHz or more. Representative examples include SiH4, Si2H6, SiH2Cl2, SiHCl3, SiCl4, It can be formed by diluting SiF4 or the like with hydrogen. One or more rare gas elements selected from the group consisting of helium, neon, argon, and krypton The silicon hydride can be diluted with hydrogen to form a microcrystalline semiconductor film. The flow rate ratio of hydrogen is set to 5 times or more and 200 times or less, preferably 50 times or more and 150 times or less, and more preferably Preferably, it is 100 times. Furthermore, when carbon dioxide such as CH4 or C2H6 is added to a gas containing silicon, It is also possible to mix in a germanium compound gas, such as GeH4 or GeF4, or F2.

[0352] In addition, the mobility of holes generated by the photoelectric effect is smaller than that of electrons, so the pin type The photodiode exhibits better characteristics when the p-type semiconductor layer side is used as the light receiving surface. The photodiode 60 is formed on the surface of the substrate 601 on which the pin-type photodiode is formed. 2 converts the received light 622 into an electrical signal. Since light from the semiconductor layer side having the opposite conductivity type becomes disturbance light, the electrode layer 642 has a light-shielding property. It is also possible to use the n-type semiconductor layer side as the light receiving surface. .

[0353] The first interlayer insulating layer 633 and the second interlayer insulating layer 634 are made of a thin film in order to reduce surface irregularities. An insulating layer that functions as a planarizing insulating film is preferable. The edge layer 634 may be made of, for example, polyimide, acrylic resin, benzocyclobutene resin, polyimide, or the like. Organic insulating materials such as ethylenediamine, propylene glycol, and epoxy resins can be used. In addition, low-k materials, siloxane resins, PSG (phosphor glass), A single layer or a laminate of BPSG (borophosphorus glass) or the like can be used.

[0354] The insulating film 631, the first interlayer insulating layer 633, and the second interlayer insulating layer 634 are made of insulating materials. Depending on the material, the method can be sputtering, spin coating, dipping, Spray coating, droplet ejection method (inkjet method), screen printing, offset printing, Forming by using roll coating, curtain coating, knife coating, etc. can be done.

[0355] By detecting light 622 incident on the photodiode 602, information on the object to be detected is obtained. When reading the information of the detected object, a light source such as a backlight is used. can be used.

[0356] The transistor 640 may be any of the transistors shown as examples in any of the first to third embodiments. Hydrogen, water, hydroxyl radicals, or hydrides (also called hydrogen compounds) can be used. By intentionally eliminating impurities, the material is highly purified, and oxygen is doped to remove oxygen. A transistor including an oxide semiconductor film containing an excessive amount of ZnO has a tendency to have fluctuations in electrical characteristics. Therefore, a highly reliable semiconductor device can be provided. can be done.

[0357] As described above, the configurations, methods, etc. shown in this embodiment may be different from the configurations, methods, etc. shown in other embodiments. They can be used in appropriate combinations.

[0358] (Embodiment 8) The semiconductor device disclosed in this specification can be applied to various electronic devices (including gaming machines). The electronic device can be, for example, a television device (television or television (also called digital receivers), computer monitors, digital cameras, digital video cameras cameras such as digital cameras, digital photo frames, mobile phones (also called mobile phones or mobile phone devices) (c), portable game machines, personal digital assistants, audio playback devices, large game machines such as pachinko machines, etc. Examples of electronic devices including the liquid crystal display device described in the above embodiment include: I will explain.

[0359] FIG. 13A shows an electronic book (also called an E-book), which includes a housing 9630, a display unit 96 31, an operation key 9632, a solar cell 9633, and a charge / discharge control circuit 9634. The electronic book shown in Figure 13(A) contains various information (still images, videos, text images, etc.) ), calendar, date or time display function, The ability to manipulate or edit the displayed information, and the ability to process it using various software (programs). In FIG. 13(A), the charge / discharge control circuit 9 As an example of 634, the battery 9635, the DC-DC converter (hereinafter referred to as the converter) ) 9636. By applying this to the part 9631, it is possible to make the electronic book highly reliable.

[0360] By using the structure shown in FIG. 13A, the display portion 9631 can be a semi-transmissive or reflective type. When using a projection type LCD display, it is expected that it will be used in relatively bright conditions, and the solar cell 633 and charging the battery 9635 can be done efficiently, making it ideal The solar cell 9633 is suitably mounted in a free space (on the front or back) of the housing 9630. This allows for efficient charging of the battery 9635. It is preferable that a lithium ion battery is used as the battery 9635. This has the advantage of enabling miniaturization.

[0361] The configuration and operation of the charge / discharge control circuit 9634 shown in FIG. 13A will be described with reference to FIG. (B) shows a block diagram and explains. Figure 13(B) shows a solar cell 9633, a battery 9635, converter 9636, converter 9637, switches SW1 to SW 3. The display unit 9631 is shown, along with the battery 9635, converter 9636, Inverter 9637 and switches SW1 to SW3 correspond to the charge / discharge control circuit 9634 This is the place to do it.

[0362] First, an example of operation when power is generated by the solar cell 9633 using external light will be described. The power generated by the solar cell is converted to a voltage that can be used to charge the Battery 9635. The voltage is increased or decreased by a inverter 9636. The display unit 9631 is operated by the solar cell. When power is used from the battery 9633, the switch SW1 is turned on, and the converter 963 7, the voltage is increased or decreased to the voltage required for the display unit 9631. When not displaying in 31, turn SW1 off and SW2 on to charge the battery. 35 charging configuration.

[0363] Next, an example of operation when external light does not generate electricity by the solar cell 9633 will be explained. The power stored in the battery 9635 is converted by turning on the switch SW3. The voltage is increased or decreased by an inverter 9637. Power will be drawn from Battery 9635.

[0364] Although the solar cell 9633 is shown as an example of a charging means, other means may be used. It may be configured to charge the battery 9635. Also, it may be configured to combine other charging means. It may be configured to perform the above.

[0365] FIG. 14A shows a notebook personal computer, which includes a main body 3001, a housing 30 3002, a display unit 3003, a keyboard 3004, etc. By applying the semiconductor device shown in this embodiment to the display portion 3003, a highly reliable notebook type It may be a personal computer.

[0366] FIG. 14B shows a personal digital assistant (PDA), and a main body 3021 includes a display unit 3023 and , an external interface 3025, an operation button 3024, etc. are provided. The semiconductor device shown in the above embodiment is shown in FIG. By applying Part 3023, it will be possible to make a more reliable personal digital assistant (PDA). can be done.

[0367] FIG. 14C shows an example of an electronic book. For example, an electronic book 2700 has a housing 2 It consists of two housings, housing 2701 and housing 2703. 03 is integrated with a shaft portion 2711, and performs opening and closing operations around the shaft portion 2711. This configuration allows the device to operate like a paper book. .

[0368] The housing 2701 incorporates a display unit 2705, and the housing 2703 incorporates a display unit 2707. The display unit 2705 and the display unit 2707 are configured to display a continuous screen. Alternatively, a different screen may be displayed. For example, a text is displayed on the right display unit (display unit 2705 in FIG. 14C) and An image can be displayed on the display unit on the side (the display unit 2707 in FIG. 14C). By applying the semiconductor device shown in the embodiment to the display portion 2705 and the display portion 2707, It can be a reliable e-book 2700.

[0369] FIG. 14C shows an example in which an operating unit and the like are provided in the housing 2701. For example, In the housing 2701, a power switch 2721, an operation key 2723, a speaker 272 5. The operation key 2723 can be used to turn pages. A keyboard, pointing device, etc. may be provided on the same surface as the display unit. In addition, there are external connection terminals (earphone terminal, USB terminal, etc.) and recording media terminals on the back and sides of the housing. The electronic book 2700 may be configured to include an insertion section or the like. It may also be configured to have a function.

[0370] The electronic book 2700 may also be configured to be capable of transmitting and receiving information wirelessly. The desired book data can be purchased and downloaded from the electronic book server. It is also possible.

[0371] FIG. 14(D) shows a mobile phone, which is composed of two housings, a housing 2800 and a housing 2801. The housing 2801 contains a display panel 2802, a speaker 2803, a microphone Phone 2804, pointing device 2806, camera lens 2807, external connection The housing 2800 is also equipped with a solar panel for charging the mobile phone. The device is equipped with a memory cell 2810, an external memory slot 2811, etc. The semiconductor device shown in the above embodiment is incorporated in the display panel 280. By applying this to 2, a highly reliable mobile phone can be achieved.

[0372] The display panel 2802 is equipped with a touch panel, and the image displayed in FIG. The multiple operation keys 2805 are shown by dotted lines. A boost circuit is also implemented to boost the input voltage to the voltage required for each circuit.

[0373] The display direction of the display panel 2802 changes appropriately depending on the usage mode. The camera lens 2807 is located on the same surface as the lens 2802, allowing video calls. The speaker 2803 and microphone 2804 are not limited to voice calls, but are also used for video calls. Furthermore, the housing 2800 and the housing 2801 can be slid apart. As shown in Figure 14(D), the unfolded state can be changed to the overlapped state, and it is portable. It is possible to make it smaller to suit the application.

[0374] The external connection terminal 2808 can be used to connect various cables such as an AC adapter and a USB cable. It is possible to charge the battery and to communicate data with a personal computer, etc. , a recording medium can be inserted into the external memory slot 2811 for storing and transferring a larger amount of data. We can handle it.

[0375] In addition to the above functions, it also has infrared communication functions, TV reception functions, etc. Good too.

[0376] FIG. 14(E) shows a digital video camera, which includes a main body 3051, a display unit (A) 3057, and a , eyepiece 3053, operation switch 3054, display unit (B) 3055, battery 3056 The semiconductor device described in the above embodiment is configured as the display portion (A) 305. 7. By applying it to the display part (B) 3055, it becomes a highly reliable digital video camera. It is possible.

[0377] FIG. 14(F) shows an example of a television device. The television device 9600 is A display portion 9603 is incorporated in the housing 9601. The display portion 9603 displays images. In addition, the housing 9601 is supported by a stand 9605. The semiconductor device described in the above embodiment is applied to the display portion 9603. This makes it possible to provide a highly reliable television device 9600.

[0378] The television device 9600 can be operated using an operation switch provided on the housing 9601 or a separate remote control. This can be done by a remote control operation device. A display unit may be provided to display information output from the device.

[0379] The television device 9600 includes a receiver, a modem, and the like. It is possible to receive general television broadcasts, and also to receive wired or wireless signals via a modem. By connecting to a communication network, it can be one-way (sender to receiver) or two-way It is also possible to communicate information in both directions (between a sender and a receiver, or between receivers). .

[0380] As described above, the configurations, methods, etc. shown in this embodiment may be different from the configurations, methods, etc. shown in other embodiments. They can be used in appropriate combinations. [Explanation of symbols]

[0381] 10 Plasma equipment 11 Substrate supply room 12 Load lock chamber 13 Transport Room 14 Cassette port 15 Vacuum Chamber 16 ICP coils 17 Gas flow path 18 First high frequency power source 19 Substrate stage 20 Substrate to be processed 21 Second high frequency power source 22 Automatic pressure control valve 23 Turbomolecular pump 24 Dry Pump 100 boards 102 insulating film 102a Insulating film 102b insulating film 103a Mask 103b Mask 104a Source electrode 104b Drain electrode 106 Oxide semiconductor film 108 Oxide semiconductor film 110 Gate insulating film 110a Gate insulating film 110b Gate insulating film 112 gate electrode 112a gate electrode 112b electrode 114 insulating film 120 transistors 130 transistors 140 transistors 150 transistors 151 insulating film 152 insulating film 154 Electrode 156 Wiring 160 transistors 164 Capacitor 180 oxygen 180a Oxygen 180b Oxygen 180c oxygen 200 boards 206 Element isolation insulating film 208 Gate insulating film 210 gate electrode 216 Channel formation region 220 Impurity region 224 Metal compound area 228 insulating film 230 insulating film 240 transistors 601 Substrate 602 Photodiode 606a Semiconductor layer 606b Semiconductor layer 606c Semiconductor layer 608 Adhesive layer 613 Substrate 622 light 631 Insulating film 633 Interlayer insulation layer 634 Interlayer insulation layer 640 transistors 641 Electrode layer 642 Electrode layer 643 Conductive Layer 644 Electrode layer 645 gate electrode 656 Transistor 658 Photodiode reset signal line 659 Gate signal line 671 Photo sensor output signal line 672 Photo sensor reference signal line 2700 e-books 2701 Housing 2703 Housing 2705 ​​Display section 2707 Display section 2711 Shaft 2721 Power Switch 2723 Operation Key 2725 Speaker 2800 chassis 2801 Case 2802 Display Panel 2803 Speaker 2804 Microphone 2805 Operation Key 2806 Pointing Device 2807 Camera lenses 2808 External connection terminal 2810 solar cell 2811 external memory slot 3001 main unit 3002 Case 3003 Display section 3004 Keyboard 3021 Main Unit 3022 stylus 3023 Display section 3024 Operation button 3025 External Interface 3051 Main Unit 3053 Eyepiece 3054 Operation switch 3055 Display section (B) 3056 Battery 3057 Display section (A) 4001 board 4002 Pixel section 4003 Signal line driver circuit 4004 Scanning line driver circuit 4005 Sealing material 4006 board 4008 Liquid crystal layer 4010 transistor 4011 transistor 4013 Liquid crystal element 4015 Connection terminal electrode 4016 Terminal electrode 4018 FPC 4018a FPC 4018b FPC 4019 Anisotropic conductive film 4021 Insulation layer 4030 Electrode layer 4031 Electrode layer 4032 Insulating film 4033 Insulating film 4510 Bulkhead 4511 Electroluminescent layer 4513 Light-emitting element 4514 Filling material 4612 Cavity 4613 Spherical particles 4614 Filling material 4615a Black area 4615b White area 9600 Television Equipment 9601 Housing 9603 Display section 9605 Stand 9630 chassis 9631 Display section 9632 Operation Key 9633 Solar Cells 9634 Charge / Discharge Control Circuit 9635 Battery 9636 Converter 9637 Converter

Claims

1. a first transistor having a first channel formation region including silicon; a second transistor having a second channel formation region including an oxide semiconductor; a capacitance element; a gate electrode of the first transistor and one of a source electrode and a drain electrode of the second transistor are electrically connected to each other; a gate electrode of the first transistor and one electrode of the capacitance element are electrically connected to each other; a first conductive layer having a region located above the first channel formation region and functioning as a gate electrode of the first transistor; a first insulating layer having a region in contact with a side surface of the first conductive layer; a second insulating layer having a region in contact with the top surface of the first insulating layer; an oxide semiconductor layer having a region in contact with a top surface of the second insulating layer and having the second channel formation region; a second conductive layer having a region in contact with the oxide semiconductor layer and functioning as one of a source electrode and a drain electrode of the second transistor; a third conductive layer having a region in contact with the oxide semiconductor layer and functioning as the other of the source electrode and the drain electrode of the second transistor; a third insulating layer having a region in contact with an upper surface of the oxide semiconductor layer; a fourth conductive layer having a region located above the third insulating layer and functioning as a gate electrode of the second transistor; when viewed in a cross section of the second transistor in a channel length direction, both end portions of the second conductive layer overlap with the oxide semiconductor layer; the third conductive layer overlaps with at least a part of an end portion of the oxide semiconductor layer in a cross-sectional view of the second transistor in a channel length direction.

2. a first transistor having a first channel formation region including silicon; a second transistor having a second channel formation region including an oxide semiconductor; a capacitance element; a gate electrode of the first transistor and one of a source electrode and a drain electrode of the second transistor are electrically connected to each other; a gate electrode of the first transistor and one electrode of the capacitance element are electrically connected to each other; a first conductive layer having a region located above the first channel formation region and functioning as a gate electrode of the first transistor; a first insulating layer having a region in contact with a side surface of the first conductive layer; a second insulating layer having a region in contact with the top surface of the first insulating layer; an oxide semiconductor layer having a region in contact with a top surface of the second insulating layer and having the second channel formation region; a second conductive layer having a region in contact with the oxide semiconductor layer and functioning as one of a source electrode and a drain electrode of the second transistor; a third conductive layer having a region in contact with the oxide semiconductor layer and functioning as the other of the source electrode and the drain electrode of the second transistor; a third insulating layer having a region in contact with an upper surface of the oxide semiconductor layer; a fourth conductive layer having a region located above the third insulating layer and functioning as a gate electrode of the second transistor; a fifth conductive layer having a region located above the third insulating layer and functioning as the other electrode of the capacitor element; when viewed in a cross section of the second transistor in a channel length direction, both end portions of the second conductive layer overlap with the oxide semiconductor layer; the third conductive layer overlaps with at least a part of an end portion of the oxide semiconductor layer in a cross-sectional view of the second transistor in a channel length direction; The second conductive layer functions as one electrode of the capacitor.

Images